Science, Faculty of
Chemistry, Department of
DSpace
UBCV
Constabaris, George
Master of Arts - MA
University of British Columbia
I. In a special form of micro gas analysis apparatus the following methods may be used to obtain quantitative separations. Carbon dioxide can be removed at 70°C. by absorption in a mixture of sodium, potassium, and lithium hydroxides. Hydrogen, in the presence of carbon monoxide and methane, can be removed by diffusion through a palladium tube at 325°C; no irregularities occur at this temperature. Carbon monoxide is quantiatively oxidized by a mixture of silver oxide and hopcalite at room temperature. Acetylene is removed by condensation in liquid air. II. The surface of an activated carbon may be oxidized by water at room temperature. The reaction produces at least 1.92 micromols of hydrogen per gram of carbon. An equilibrium is established between the hydrogen, water, and the surface complex, after relatively long periods of time. The nature of the complex is not indicated.
37 C £ <&g> PART I - STUDIES II THE MICROANALYSIS OP GASES PART II - THE CHEMISORPTIOH OF WATER BY AH ACTIVATED CARBON GEORGE COE3TABARIS A thesis submitted i n partial fulfilment of the requirements for the Degree of MASTER OF ARTS In the Department of CHEMISTRY The University of Brit i s h Columbia. April, :1948. ABSTRACT I . I n a s p e c i a l form of micro gas a n a l y s i s apparatus the f o l l o w i n g methods may be used to o b t a i n q u a n t i t a t i v e s e p a r a t i o n s . Carbon d i o x i d e can be removed a t 70°C. by a b s o r p t i o n i n a mixture of sodium, potassium, and l i t h i u m h y d r o x i d e s . Hydrogen, i n the presence of carbon monoxide and methane, can be removed by d i f f u s i o n through a p a l l a -dium tube a t 32j>°C; no i r r e g u l a r i t i e s occur a t t h i s temper-ature* Carbon monoxide i s q u a n t i a t i v e l y o x i d i z e d by a mixture of s i l v e r oxide and h o p c a l i t e a t room temperature. A c e t y l e n e i s removed by condensation i n l i q u i d a i r . I I . The s u r f a c e o f an a c t i v a t e d carbon may be o x i d i z e d by water a t room temperature. The r e a c t i o n produces at l e a s t 1.92 micromols of hydrogen p e r gram of carbon. An e q u i -l i b r i u m i s e s t a b l i s h e d between the hydrogen, water, and the s u r f a c e complex, a f t e r r e l a t i v e l y l o n g p e r i o d s of time. The nature of the complex i s n o t i n d i c a t e d . ACKNOWLEDGEMEHT I wish t o take t h i s o p p o r t u n i t y to express my s i n c e r e thanks t o Dr. M. J . M a r s h a l l , who d i r e c t e d t h i s r e s e a r c h . TABLE OF CONTENTS INTRODUCTORY NOTE 1 PART I - I INTRODUCTION 4 II DESCRIPTION OF ANALYSIS APPARATUS 7 III METHODS OF OBTAINING THE PURE GASES 10 IV EXPERIMENTAL RESULTS 14 V .SUMMARY 24 PART II I INTRODUCTION 26 II APPARATUS 28 III EXPERIMENTAL 33 IV DISCUSSION 47 V SUMMARY 49 BIBLIOGRAPHY 50 1 INTRODUCTORY NOTE The d i v i s i o n of t h i s t h e s i s i n t o two separate p a r t s , one p e r t a i n i n g to the m i c r o a n a l y s i s of gases, the o t h e r to the c h e m i s o r p t i o n of water vapor by an a c t i v e carbon, i s n e c e s s a r y f o r c l a r i t y o f p r e s e n t a t i o n . The study of the o x i d a t i o n o f the carbon s u r f a c e by water depends on the a c c u r a c y of the a n a l y s i s o f the produced gases, but the type of a n a l y s i s i s d i c t a t e d by these p r o d u c t s . The two p a r t s a r e , t h e r e f o r e , complementary and so, c h r o n o l o g i c a l l y a t l e a s t , t h e r e was a d e f i n i t e amount o f o v e r l a p p i n g i n the work, i n v e s t i g a t i o n of the a n a l y s i s b e i n g c a r r i e d out s i m u l t a n e o u s l y w i t h the study of c h e m i s o r p t i o n . A few y e a r s ago H . McMahon found t h a t a c e r t a i n . s a m p l e of a c t i v e carbon would reduce up to about 60 micro-mols per gram of carbon d i o x i d e . An e q u i v a l e n t amount of carbon monoxide c o u l d be pumped o f f the c h a r c o a l between room temperature and 500°C, and another e q u i v a l e n t amount of the same gas c o u l d be o b t a i n e d by o u t g a s s i n g up t o 1100 oC* These r e s u l t s i n d i c a t e d t h a t the carbon d i o x i d e was reduced t o carbon monoxide, and t h a t a very s t a b l e carbon-oxygen s u r f a c e complex was formed. However, i t c o u l d not be d e f i n i t e l y s t a t e d t h a t the carbon d i -oxide i t s e l f was not ohemisorbed, and t h a t on subsequent heat-i n g the s u r f a c e complex thus formed broke up t o y i e l d o n l y carbon monoxide. A b e t t e r u n d e r s t a n d i n g of the r e a c t i o n mechanism c o u l d be o b t a i n e d o n l y by d e t e r m i n i n g whether or not carbon was d e p o s i t e d from the gas phase. I f the carbon i n the carbon monoxide recovered at the lower temperatures originated i n the carbon dioxide, and not from the carbon itself,'then the reac-tion would be as McMahon postulated. To elucidate this prob-lem i t was decided to attempt the oxidation of the surface with water vapor. If a reaction parallel to that with carbon d i -oxide occurred, and the mechanism was that suggested, then i t would be expected that hydrogen would be produoed, and that no carbon monoxide would be recovered except at elevated tempera-tures. If these phenomena were observed, this would constitute definite proof that the oxidation at low concentrations of adsorbate occurs only at the points with a high energy of activation, and that no oarbon from the gas phase i s l a i d down on the surface. In order to study the proposed reaction a system of analysis was needed. A method of analysis of small amounts of gas of the order of 1 0 ou.mm. has received careful attention i n the laboratories here, but i t was necessary to adapt this method for hydrogen, since this gas was one of the expected products. Some years ago Dr. Marshall had shown that hydrogen could be analyzed i n this type of apparatus using a heated palladium tube. However, certain irregularities have appeared (which vti.ll be noted later) when this method for hydrogen i s used i n other types of apparatus, so i t was desirable to examine i t more c r i t i c a l l y . This work was started by myself, working for Dr. Marshall, and comprises Part I of this thesis. The study of the oarbon water reaction was commenced at the same time by P. McGeer, also working for Dr. Marshall, who, i n the short time t h a t he had f o r t h i s work, was ab l e t o o b t a i n some v a l u a b l e r e s u l t s , i n p a r t i c u l a r , t h a t hydrogen a c t u a l l y was formed a t room temperature. The continuance of t h i s work by m y s e l f i s g i v e n i n P a r t I I . 4. PAST I - STUDIES IH THE MICROANALYSIS OF GASES I. INTRODUCTION The quantiative study of minute quantities of gases i s essential i n a variety of f i e l d s and consequently the l i t e r a -ture contains a great deal of research dealing with this prob-lem 1. The method of analysis developed here over a period of time i s more simple' than most of the different types that have been demonstrated, and i s Just as versatile with regard to the applicability to different gases, the quantity of gas analyzed, and the accuracy obtained. The method has been adequately p discussed elsewhere, and only when necessary w i l l specific reference to manipulation be given. This part of the work deals primarily with the pos-s i b i l i t y of using a palladium tube to separate hydrogen from a gas mixture containing oarbon monoxide, methane, and hydrogen* The use of palladium for this purpose apparently presents some d i f f i c u l t i e s . The rate of diffusion of hydrogen through palla-dium becomes appreciable only at temperatures above 260°C.2 It has been shown that stopcock vapors and greases, 4 and hydro-oarbons^ poison the palladium. Smithies^ also states that after 5. hydrogen has diffused through palladium for some time at 500°C the process stops, and the palladium must be retreated by oxi-dation at a red heat, followed by reduction with hydrogen at 150°C. Fleiger-5 constructed an analysis apparatus with which he studied the use of a palladium tube for the analysis of hy-drogen i n the presence of carbon monoxide and methane. Using this apparatus he found i t possible to obtain an accurate anal-ysis for hydrogen only i f not over 5 per cent of methane and 9 per cent of carbon monoxide were present* These limitations were attributed to the following reactions catalyzed by palla-dium at 300°C. (1) 2C0 - C0 2 + C (2) CO + 3H2 •» H20 + CH4. (3) CH4 - C + 2H2 The free energies for these reactions at 600°K are: AF = -15,727 oals* A F - -17,256 cals, AF - +5,490 cals respect!vely6. However, Taylor and MoKinney state that reac-tions (1) and (3) do not occur on massive palladium at 300°C.7. Whatever the discrepancies may be due to in Fleiger's apparatus, the conditions of the analysis were very different from those in the apparatus used here, so this work did not rule out the use of palladium. The analysis of carbon monoxide in the presence of methane requires special methods because each on oxidation gives carbon dioxide* Branford and Baldwin state that cupric oxide w i l l oxidize carbon monoxide only at 300°C, and that i t w i l l oxidize methane at 900°C,® and preferential oxidation i s usually oarried out i n the analysis of gas mixtures containing these two gases. A more refined method involves the oxidation of carbon monoxide by oupric oxide at 300°C, followed by the oxidation of methane on Arneil fs oatalyst9 also at 300°C. Because suoh selective oxidation necessarily requires flow methods, i t s use i s limited and can not readily be applied to the apparatus used here. Browning, 1 0 using the method of this work, used a silver oxide, mixed with hopoalite to serve as a catalyst, to oxidize carbon monoxide at room temperature, and i t has been recently reported that this mixture w i l l permit the oxidation of carbon monoxide i n the presence of hydrogen 1 1, which does not seem to 12 be possible with silver oxide alone . The use of this reagent was checked and the readings are given below. More recently, red murcuric oxide has been proposed for this purpose 1^ The analysis of oarbon dioxide by the use of a low melting point hydroxide mixture has been discussed previously 2 and only the f i n a l work i s given below. McGeer 1 4, in his work on the oarbon chemisorption of water, found the presence of a condensable gas which he took to be acetylene, so in the latt e r part of this work acetylene was generated and examined for possible analytical procedure. The vapor pressure of acetylene at liquid a i r temperature i s 6 x lO""-^ mm. of meroury1^ and can thus be completely removed by condensation in the li q u i d a i r tip* I I . DESCRIPTION OF ANALYSIS APPARATUS The gas a n a l y s i s used t o i n v e s t i g a t e the a b s o r p t i o n of carbon d i o x i d e was the one d e s c r i b e d p r e v i o u s l y . 2 The base t i p on t h i s apparatus was then r e p l a c e d by a p a l l a d i u m - s o f t g l a s s t i p , which u n f o r t u n a t e l y c o u l d not be ground i n t o the c a p i l l a r y . T h i s extreme disadvantage was overcome by the method noted below* The other t i p was r e t a i n e d as a l i q u i d a i r con-densing t i p . Because t h e r e were on l y two t i p s on t h i s stopcock no complete a n a l y s e s were made* When ne c e s s a r y , the p a l l a d i u m t i p was removed and a quartz t i p , c o n t a i n i n g o x i d i z e d oopper wi r e , was s u b s t i t u t e d . Thus i t was p o s s i b l e t o cheek t h e p u r i t y of the gases by o x i d a t i o n . The p a l l a d i u m tube was heated w i t h a s m a l l f u r n a c e whioh c o n s i s t e d of a few t u r n s of nichrome w i r e wound around a q u a r t z tube of .6 mm. diameter, and i n s u l a t e d w i t h asbestos* The h e a t e r would m a i n t a i n a temperature o f 400°C w i t h 1.2 amps. The temperature was measured w i t h a ohromel-alumel thermocouple i n s e r t e d i n t o the q u a r t z tube. The c u p r i c oxide was r a i s e d to a r e d heat by a p p l i -c a t i o n of the oxygen t o r c h . • • . Throughout the f i r s t p a r t of the work i t became i n -c r e a s i n g l y obvious t h a t the a n a l y s i s t i p s would have to be put i n t o the apparatus w i t h ground-rglass c o n n e c t i o n s . The p i c e n e , which was used to s e a l the t i p s i n , would become heated, and because i t exposed a f a i r l y l a r g e a r e a t o the vacuum, a 8. great deal of carbon dioxide would be given off, and also, the picene would poison the palladium. The action with the quartz-cuprio oxide t i p was also quite poor. Since quartz Is a fairly-good conductor of heat, when the ouprio oxide was heated the picene decomposed with carbon dioxide formation which made analysis unreliable. When i t was f i n a l l y possible to construct a more reasonable apparatus a method for making small inter-changeable ground glass connections was developed. The f i n a l form of the apparatus i n whioh the connections were used was extremely satisfactory with regard to the gases driven off on heating, and with regard to manipulation* The apparatus was modified somewhat i n order that the tips would not have to be evacuated through the analysis gauge. This was accomplished by using a three-way capillary stopcock, the single arm being f i t t e d with a ground joint with which the whole tip assembly was attached. The advantage of this modifi-cation i s that the tips could be removed completely when neces-sary. One of the other arms led directly to a high vacuum lin e , the other formed the capillary of the analysis gauge. The c a l i -bration of this gauge w i l l be found In Part II. The description of the method for making the small interchangeable ground glass joints requires some detail . Because of volume considerations these connections had to be very small, and i t i s very hard to form such small parts by rotation i n the blast lamp, even to a taper close enough to grind into a metallic j i g . It was, therefore, necessary to devise some means by which they could be formed to the correct 9 . t a p e r b e f o r e g r i n d i n g . A s i x mm. oarbon e l e c t r o d e was t u r n e d down i n a p e n c i l sharpener and then i t was broken o f f about f i v e mm. from the t a p e r ( (1) F i g u r e I ) • T h i s form was as s h o r t as p o s s i b l e because of the h i g h s p e c i f i c heat o f the carbon. F o r the o u t e r p a r t of the j o i n t t e n mm..tubing was drawn down to the approximate t a p e r w i t h t h i c k e n e d w a l l s as shown i n ( 2 ) . The carbon F i g u r e I . form was then i n s e r t e d , and the g l a s s moulded to the form u n t i l i t f i t t e d v e r y c l o s e l y . The g l a s s was allowed t o c o o l j u s t beyond the a n n e a l i n g temperature and the carbon form shaken out. The p a r t was trimmed t o s i z e by c u t t i n g i t a t A and then g r i n d i n g i t w i t h a stone wheel t o the s t a r t of the t a p e r a t B. The i n n e r p a r t , ( 3 ) , was moulded i n the same f a s h i o n , but the w a l l s were not t h i c k e n e d i n the o r i g i n a l pulldown, but were kept as t h i n as p o s s i b l e w i t h the same t h i c k n e s s everywhere a l o n g the t a p e r . Thus the o u t s i d e of the g l a s s w a l l had the same t a p e r as the carbon form. The bulge l e f t at C was p u l l e d down by hand, and the tube c o l l a p s e d a t D f o r j o i n i n g t o the a p p r o p r i a t e c a p i l l a r y t u b i n g . The o u t e r and i n n e r p a r t s were ground i n t o each o t h e r , and because of the forming were almost i n t e r c h a n g e a b l e . I f a 10. better seat Is desired i t could easily be obtained by making two metallio jigs of the same dimensions of the carbon form, and then grinding the formed glass tapers into these. Because of the original closeness of the f i t , l i t t l e grinding would be necessary and therefore the jigs could be used for a long time before they beoame deformed. The outer parts were sealed to a piece of semi-capil-lary tubing drawn down from 16 mm. tubing. The palladium con-nection was made by making a soft glass inner part and collap-sing this at D around the palladium tube. A vacuum tight seal could not be obtained this way but when the joint was covered with pioene i t was satisfactory. In a l l , five tips were placed on the assembly. These were the palladium, quartz copper-oxide, condensing, base mix-ture and silver oxide tips. The l a t t e r two were separated from the assembly by small stopcocks. This was the f i n a l form of the apparatus used in Part II. Most of the readings i n Part I were made with the earlier apparatus. III. METHODS OF OBTAINING THE PURE GASES In this work i t was necessary to use small amounts of pure gases, and also to be able to obtain them easily arid quickly when desired. The usual methods of preparation require elaborate purification and involve large quantities of materials. The systems developed herein overcame these disadvantages with-out sacrifice of purity. The time taken to regenerate a new DIAGRAM I 1 1 . l o t of gas was about one h a l f - h o u r . The main disadvantage of the methods i s t h a t the gases are s t o r e d at low p r e s s u r e s and t h e r e f o r e , become s l o w l y contaminated due t o d e s o r p t i o n o f f o r e i g n gases from the w a l l s of the storage f l a s k s . By repeated degassing and f i l l i n g o f these storage b u l b s the amount o f i m p u r i t y becomes n e g l i g i b l e . The g e n e r a t i n g apparatus f o r hy-drogen, methane and carbon monoxide i s shown i n Diagram I . Hydrogen was o b t a i n e d by the a c t i o n of water on potas-sium. I n p r e l i m i n a r y experiments the water was outgassed by merely drawing o f f the vapor phase a few times. Subsequent a n a l y s i s of the hydrogen showed the presence o f o t h e r gases which proved t o have o r i g i n a t e d i n the water as d i s s o l v e d i m p u r i t i e s . To overcome t h i s d i f f i c u l t y the f o l l o w i n g procedure was adopted. Water, d i s t i l l e d over permanganate t w i c e , was s e a l e d i n t o the tube R4, and the system evacuated. The s t o p -oock above the water tube was opened, and a s m a l l amount of water was condensed i n t o the l i q u i d a i r t r a p Rjj, The system was evacuated f o r f i f t e e n minutes. As w i l l be shown i n P a r t I I t h i s method i s v e r y e f f e c t i v e f o r p u r i f y i n g water. P r e v i o u s l y m e t a l l i c potassium had been s e a l e d i n t o R£, and the potassium d i s t i l l e d , under h i g h vacuum, i n t o R7. R& was then s e a l e d o f f the apparatus. The condensed water vapor was melted and i n t r o -duced to the d i s t i l l e d potassium. The hydrogen so produced was expanded i n t o the storage bulb S i . The p u r i t y of the hydrogen was t e s t e d i n the f o l l o w i n g manner. L i q u i d a i r was p l a c e d on the t r a p T, so t h a t any water vapor would be removed, and the hydrogen i n the storage bulb was completely expanded i n t o the I" 12. gas analysis apparatus, where i t gave an unreadably high pressure (ahout 10"*1 cms.). It was admitted to the palladium tip at 375°C and after ten minutes only .3 to .5 x 10" 4 cms. of gas were l e f t . Thus the hydrogen made i n this manner i s exceptionally pure. The synthesis of pure methane proved more d i f f i o u l t . The usuall method for obtaining methane1**, involving the cata-l y t i c combination of oarbon monoxide and hydrogen over oopper, with subsequent fractional d i s t i l l a t i o n of reaotants and products, was of l i t t l e use. The f i r s t method attempted was the cracking of acetone by an. incandescent tungsten filament followed by condensation of the excess aoetone and the produoed Ketene 1 7, but oxidation of the gases thus produced showed the presence of a more than one oarbon gas. The next method used was a modified Grignard synthesis which proved satisfactory* Methyl magnesium iodide was made i n the accepted manner and a few mis. of the ether solution were introduced into the tube T i , care being taken not to permit any of the reagent to touch the glass where the seal-in was to be made. The solution was frozen with liquid a i r so that the re-agent oould be safely sealed into the system. The methane generator was degassed thoroughly with the diffusion pump while the reagent was frozen. To remove the ether the li q u i d a i r was removed from T i and placed on another tube not shown, whereupon the ether d i s t i l l e d out of the reagent. After most of the ether had been removed, the trap containing i t was sealed off. The residue from the reagent was a colorless, amorphous solid. There 1 3 . seems to be no r e f e r e n c e t o the d i s t i l l a t i o n of G r i g n a r d r e -agents a t t h i s temperature a l t h o u g h at h i g h e r temperatures the reagent i t s e l f w i l l d i s t i l 1 * * , i t may be noted I n p a s s i n g t h a t i t i s u n f o r t u n a t e t h a t the d i s t i l l a t e was not t e s t e d f o r the presence of the G r i g n a r d reagent. The remaining e t h e r was removed by e v a c u a t i o n . Water vapor, p u r i f i e d by the method above, was i n t r o d u c e d , and the r e s u l t i n g methane expanded through the l i q u i d a i r t r a p Tz, i n t o the storage bulb Sz.. The p u r i t y of the methane, a f t e r the storage bulb had been f l o o d e d w i t h i t r e p e a t e d l y , was 9 9.6 p e r c e n t , as shown by o u p r i c oxide o x i d a t i o n and condensation of the r e s u l t a n t carbon d i o x i d e . Carbon monoxide was s y n t h e s i z e d by the method of Thompson 1? P u r i f i e d f o r m i c a c i d 2 0 was s e a l e d i n t o Rz. I t was f r e e d of d i s s o l v e d gases i n the same manner as the water vapor. The vapor was passed through phosphorous pentoxide i n Ri and the carbon monoxide s t o r e d i n S3. T h i s method produced some unexpected d i f f i c u l t i e s . The f i r s t was the incomplete removal of the f o r m i c a c i d by the phosphorous p e n t o x i d e . T h i s was over-come by use of the l i q u i d a i r t r a p T^, The second was the p r o d u c t i o n of hydrogen i n the r e a c t i o n to the extent of about 2 per cent by volume. That t h i s gas was hydrogen was shown by the s i m i l a r i t y i n b e h a v i o r on t r e a t i n g the gas w i t h heated p a l l a d i u m and on o x i d a t i o n . I n a l l oases the carbon monoxide was t r e a t e d w i t h heated p a l l a d i u m b e f o r e any r e a d i n g s were made. Carbon d i o x i d e was o b t a i n e d by a method p r e v i o u s l y d e s c r i b e d 2 . A c e t y l e n e was s y n t h e s i z e d from c a l c i u m c a r b i d e and 14 water vapor* The apparatus f o r t h i s i s not shown. The water vapor was p u r i f i e d as above and the a c e t y l e n e f u r t h e r p u r i f i e d by repeated s o l i d i f i c a t i o n and o u t g a s s i n g . The t h r e e s e t s of double s topcocks i n Diagram I p e r -m i t t e d the i n t r o d u c t i o n of the c o r r e c t amount of gas i n t o the a n a l y s i s gauge. I T . EXPERIMENTAL RESULTS (1) THE ABSORPTION OP CARBON DIOXIDE (a) P r e p a r a t i o n of the Reagent. The c o m p o s i t i o n of the base m i x t u r e used was as f o l l o w s : Hydroxide % by Weight M a n u f a c t u r e r ' s A n a l y s i s L i OH 2.6 NaOH 23.6 Assay - 97% ( H 2 0 - 1.5%) KOH 73*8 ". - 85.6% ( H 2 0 - 13%) As i s seen, t h e r e i s a l a r g e percentage of water i n the m i x t u r e . The m i x t u r e was prepared i n the f o l l o w i n g manner. The three s o l i d h y d r o x i d e s , i n the above p r o p o r t i o n s , were heated u n t i l a mol ten s o l u t i o n r e s u l t e d (350°G) . T h i s was c o o l e d to 8 l°C and m a i n t a i n e d a t t h i s temperature f o r an hour* The r e m a i n i n g l i q u i d was decanted from the s o l i d phase w h i c h had s e t t l e d o u t , and i t was a l l o w e d t o c o o l t o 7 5 ° C T h i s a l s o was kept a t t h i s temperature f o r an hour and a g a i n the super -natant l i q u i d was decanted . T h i s was the reagent u s e d . _ _ _ _ _^ 15. • (b) Error introduced due to the volume of the tips* In order to measure the volume of the tips so that the gauge error in analysis oould be estimated, a i r was admitted to the gauge and the pressure read at a calibrated mark with the stopoook closed, and then read at the same mark with the stopcock open. These pressures were 22.4 cms. of Hg and 2*5 cms. of Hg, respectively. The volume of the capillary above the calibrated mark was .0841 cos. The volume of the tips i s given by the expression: .0841 x 22.4 - .0841 » *75 oc. 2.5 This volume therefore introduced a loss of .75/145.2 x 100 a *5%» (where 145.2 was total volume of the gauge) of the gas originally present. However, i t i s obvious that there w i l l be no error due to the tip volume i f the gas i s introduced to both gauge and tips before i t s pressure i s read. (o) The Rate of Absorption at Room Temperature. To find the rate of absorption of carbon dioxide by the mixture at room temperature, (19°C - 22°C), known amounts of gas were admitted to the tips and l e f t for various times. Pressure of CO2 admitted Time (hours) Pressure of COpleft 25.8 cms. 17.5 24.9 24.4 " 252. 22.4 From these data i t i s seen that the mixture absorbs carbon dioxide very slowly at room temperature, and therefore i t i s not necessary to separate the base tip by means of a stopcock. 16, (d) Measurement of Oarbon Di o x i d e U s i n g L i q u i d A i r . I t was found t h a t the quick-e s t method to o b t a i n complete condensa-t i o n of the oarbon d i o x i d e i n the l i q u i d a i r t i p was to move the l i q u i d a i r bath up the t i p i n stages o f about one q u a r t e r of l e n g t h o f the t i p , l e a v i n g the bath at each i n t e r v a l f o r about two minutes. I f t h i s was not done, the t i p b e i n g completely immersed immediately, the time taken f o r complete condensation, (measured by a l t e r n a t e l y F i g u r e I I condensing and v a p o r i s i n g the gas) was about twenty, minutes. A p p a r e n t l y the t i p has such a narrow i n s i d e diameter t h a t the s o l i d carbon d i o x i d e formed a t the s u r f a c e of the l i q u i d a i r b l o c k s o f f the r e s t of the t i p , a l l o w -i n g the oarbon d i o x i d e a c c e s s t o o n l y a s m a l l a r e a at a tempera-t u r e low enough to condense i t . (e) Measurement of Oarbon D i o x i d e U s i n g the M i x t u r e of Bases. The most convenient form i n which t o ' i n t r o d u c e the base i n t o the f i n e t i p T i i s as a powder. I t c o u l d be poured i n as a l i q u i d but t h i s method i s very i n c o n v e n i e n t s i n c e the f u n n e l , drawn down v e r y f i n e , and the t i p , must be kept a t an e l e v a t e d temperature. However, the powdery form absorbs l a r g e q u a n t i t i e s of water and t h e r e f o r e must be outgassed. The out-g a s s i n g was con t i n u e d u n t i l constant r e a d i n g s of the p r e s s u r e * ._. . 17. a f t e r l i q u i f y i n g and s o l i d i f y i n g the base, were obtained* I t may be noted again that any water absorbed changes the compo-s i t i o n of the mixture, as do subsequent chemical reactions. Such reactions, since they involve only minute amounts gas (1 omm.), a l t e r the melting point only s l i g h t l y , thus permit-t i n g a large number of analyses with each charge of base. On the other hand the absorbed water tends to lower the melting point, and further i t i s reabsorbed when the base cools. However, due to other considerations i t i s necessary to outgas most of the water. In analysis constant r e s u l t s are obtained only i f the gas i s l e f t over the s o l i d i f i e d base f o r at l e a s t f i v e minutes, whioh i s s u f f i c i e n t time to permit the base to reabsorb the water vapor* (f) Method of Analysis Using L i q u i d A i r and then the Mixture. In the previous paper 1 s a t i s f a c t o r y r e s u l t s were not obtained because the precautions of 5 and 6 were not followed. I t i s worthwile, therefore, to outline the procedure which gave the r e s u l t s noted below. i . Gauge the t i p s evacuated, i i . S i and S 2 closed, mixture of a i r and C 0 2 admitted to gauge. i i i . Pressure measured, mercury lowered a safe distance, S i opened, l i q u i d a i r bath r a i s e d . A f t e r f i v e minutes the mercury r a i s e d as close to S i as possible, i v * Mercury lowered to B, Si closed, l i q u i d a i r removed, 1 8 . new p r e s s u r e r e a d . (Time of a n a l y s i s - 1 5 mins.) v, S 2 opened, mercury lowered a safe d i s t a n c e , Si opened, h e a t e r t u r n e d on. A f t e r the base becomes molten the mercury i s moved to S]_. v i * Heater t u r n e d o f f , f i v e minutes l a t e r mercury lowered to B, c l o s e d , new p r e s s u r e r e a d . (Time of a n a l y s i s -1 5 mins.) (g) R e s u l t s . I n i t i a l p r e s s u r e Approximate volume . % C 0 2 u s i n g % C 0 2 u s i n g o f mixture a t Bar, p r e s s u r e . l i q u i d a i r mixture* 18.2 cms. 1 8 . 2 cmms. 35 .7 35.7 13*3 " 13.3 n 39.1 39.1 13*5 " 13.5 tt 51.2 31.2 10.3 rt 10.3 n 57 .5 57.5 18.9 " 18.9 n 62 .5 61.9 1 7 . 8 » 1 7 . 8 « 68.0 67.2 1 6 . 3 " I6.3 tt 78 .5 78.5 3.3 » 3.2 11 82.0 83 .5 (h) Temperature and Rate of A b s o r D t l o n . S e v e r a l p r e l i m i n a r y experiments i n d i c a t e d t h a t the amount of a b s o r p t i o n at temperatures below the m e l t i n g depended on the time t h a t the gas was l e f t over the base. I t seems reasonable to assume t h a t the C 0 2 i s completely absorbed when the base reaches i t s m e l t i n g p o i n t . T h i s c o u l d not be measured because of the water vapor d r i v e n o f f . In order t o measure the temperature at which complete a b s o r p t i o n takes p l a c e the gauge and t i p s were evacuated and an amount of C 0 2 admitted to the gauge ( S i c l o s e d ) . The t o t a l amount 19. n of COg present was measured by using l i q u i d a i r . Since the | amount of C0 2 absorbed by the base depends on the time, an a-r-1 bitrary time of five minutes over the base at the particular temperature of the reading was allowed. After each temperature reading had been made a pressure reading was taken to ascertain the amount of G02 absorbed. Pressure of gas mixture; 5 •7 cms. C0 2 (Liq. air) 5.2 cms. Temperature Time Heated -Time Cooled Pres. of Gauge 64° 5 mins. 5 mins. 4.8 cms. 75° n it 1*5 " Pressure of gas mixture: 10.3 cms. » tt C0 2 (Liq* air) 4.5 " it n residue: 5.8 " Temperature Time Heated Time Cooled Pres. of Gauge 58° 3 mins. 5 mins. 8.5 cms. 64° tt » 5.8 » Pressure of Gas Mixture: 17.8 cms. M it C0 2 (Liq. air) 5.6 '» tt II residue 12.2 Temperature Time Heated Time Cooled Residual Pres. 48° 5 mins. 5 mins. 17.25 cms. 53° n . it 16>9 » 58° tt tt 16.4 » 64° it it 14.4 " 70° ii it 12.2 » 20. The above r e s u l t s show t h a t a b s o r p t i o n takes p l a c e f a i r l y r a p i d l y a t temperatures f a r below the m e l t i n g p o i n t . I n f a c t they i n d i c a t e t h a t a mixture c l o s e r t o the e u t e c t i c might absorb COg completely a t room temperature. However, complete a b s o r p t i o n takes p l a c e at around 70°, the time, 5 minutes* Lower temperatures can be used but times must be l o n g e r . (2) THE USE OF A PALLADIUM TUBE FOR THE ANALYSIS OF HYDROGEN, (a) A c t i o n o f the Hydrogen i n the P a l l a d i u m Tube. The r a t e of d i f f u s i o n of the hydrogen through the p a l l a d i u m tube depends both on the temperature and on the a r e a heated. The r e a d i n g s below show the e f f e c t of temperature on the r a t e f o r the same ar e a heated. The p r e s s u r e s shown are not those a t whioh d i f f u s i o n took p l a o e , but are the v a l u e s read when the gas was drawn out o f the t i p s by l o w e r i n g the mercury to the l e v e l B (thus s t o p p i n g the d i f f u s i o n ) , and then compres-sed a g a i n by r a i s i n g the mercury t o l e v e l A. The a c t u a l p r e s -sure i s t h e r e f o r e the p r e s s u r e noted m u l t i p l i e d by the r a t i o of volume between A and t o the volume above A, i n c l u d i n g the t i p s . P r e s s u r e (cms, of Hg) Time (mins.) Temperature °C. 19.2 0 288 12.15 5 284 7.8 13 284 4.2 20 286 29.5 0 336 .4 5 336 29.0 0 380 .0 5 38O 21. It i s seen from these readings that a temperature as low as 32.5°C may reasonably be used. As low a temperature as possible i s desirable because of the reactions with carbon monoxide and methane noted i n the introduction. (b) Action of Carbon Monoxide i n the Palladium Tube. It has been stated that the carbon monoxide used contained a small percentage of hydrogen. Accordingly, when the carbon monoxide was put into the palladium tube part of the gas disappeared. This was not due to reaction (l) of the introduotion because no carbon dioxide was produced. Two other facts which make this point conclusive were: no further shrinkage took place after the f i r s t few minutes of heating; oxidation of the carbon monoxide by cupric oxide showed the same percentage loss. In order to examine the temperature at which reaction (1) began to have a noticeable effect, carbon monoxide was introduced Into the palladium tube and the temperature raised to 450°C. After the i n i t i a l loss, no added shrinkage occurred, and no carbon dioxide was formed after one halfVhour at this temperature. To put this conclusion to a more stringent test a small piece of palladium was inserted i n a quartz tip and some carbon monoxide admitted. The palladium was heated to a red heat and no contraction was observed, and no carbon dioxide was produced. It i s therefore seen that as far as reaction (1) i s concerned, i t does not take place under the conditions of this analysis. The main conditions which seem to affect i t are: 22. the s t a t e of the p a l l a d i u m , the p r e s s u r e of carbon monoxide, and the temperature of the p a l l a d i u m . (o) A o t i o n of Methane i n the P a l l a d i u m Tube. No c o n s i s t e n t r e a d i n g s of the a c t i o n of heated p a l -l a d i u m on methane were o b t a i n e d (see r e a o t i o n (2), I n t r o d u c t i o n ) . From the data whioh were ob t a i n e d i t appeared t h a t above 350°C. r e a o t i o n (2) d i d occ u r . (d) A n a l y s i s o f Hydrogen-Methane, and Hydrogen-Carbon Monoxide M i x t u r e s . $ by Volume V o l . of Sample H 2 CO CH4 N.T.P.(oommsi) Time (mins) Tempera-t u r e °C. %H 2 Found Deviat: 41.7 58.3 21 10 410 42 .2 + .5 69.8 30.2 2P.6 10 370 71.7 + .9 2.4 97.6 6.5 5 360 3*92 +1.5 70.0 30.0 22 6 340 70.0 0 35.3 64-. 7 20.8 15 310 35.3 0 80.8 19.2 31.5 15 310 80.8 0 85i7 14.3 8.6 7 380 85.7 0 82.9 17.1 9.6 20 310 82.9 ' 0 78.1 21.9 4.2 5 380 78.1 0 67.0 33*0 5.0 6 385 67.O 0 59.8 41.2 3.5 3 390 59.8 0 52.0 48. 6.5 6 390 52*0 0 5O.O 50 7.8 3 370 50*0 0 44.3 55.7 12.2 11 310 44.3 0 43.6 56.4 8.0 6 360 43.6 0 34.3 75.7 10.8 3 380 35.1 + .8 33.3 76*7 9.9 3 430 31.5 -1.8 23. The t a b l e shows the f o l l o w i n g f a e t s . I f the tempera-t u r e of the p a l l a d i u m i s too h i g h when mixtures o f methane and hydrogen are an a l y z e d the r e s u l t s f o r hydrogen w i l l be too high* The lowest temperature f o r whioh t h i s ooours i s s t i l l h i g h enough t o permit the hydrogen t o d i f f u s e through a t a f a s t r a t e . There appears to be no d i f f i c u l t y i n a n a l y z i n g a gas mixture of carbon monoxide and hydrogen f o r hydrogen. (3) THE OXIDATION OP CARBON MONOXIDE BY SILVER OXIDE. These readings were made f o r carbon monoxide alone, no a n a l y s i s of mixtures being attempted. During the o x i d a t i o n , c a r r i e d out a t room temperature the condensing t i p was su r -rounded by l i q u i d a i r t o remove the carbon d i o x i d e formed. The oarbon d i o x i d e must be removed i n order t o prevent the fo r m a t i o n o f s i l v e r carbonate, the oxide b e i n g b a s i c . H o p o a l l t e , 50 peroent by weight i n the mixture w i t h s i l v e r oxide* was used t o c a t a l y z e the r e a c t i o n . The f o l l o w i n g r e a d i n g s i l l u s -t r a t e the a c t i o n : P r e s s u r e of CO Time f o r o x i d a t i o n P r e s s u r e of COg ^COg cms. mins* cms. l o st 18.9 10 18.2 3.7 19.2 15 18.1 3.7 37.5 20 34.7 7.4 The t a b l e shows t h a t the amount of oarbon d i o x i d e l o s t as the carbonate depends mai n l y on the time. One disadvantage of t h i s method f o r the a n a l y s i s of oarbon monoxide i s t h a t the h o p c a l i t e - s i l v e r oxide mixture soon l o s e s i t s a c t i v i t y . 24. (4) THE CONDENSATION OF ACETYLENE AT LIQUID AIR TEMPERATURE. No analyses of gas mixtures were made i n this oase* The readings made with aoetylene were merely performed in order to show that the aoetylene oould be completely condensed at l i q u i d a i r temperature. This proved to be the case. V. SUMMARY. In this work i t has been found, using a special form of micro gas analysis apparatus, that carbon dioxide may be removed from a gas mixture by absorption of a mixture of solid hydroxides at 70°C. The use of li q u i d a i r for this purpose has some advantages over this method among which are: the tip required i s very much smaller; the condensed gas can be recovered for reexamination; i t i s handled much more easily. Nevertheless, i f liquid a i r i s not available, or a totall y selective reagent i s required, the mixture i s dependable to give results within the same limits of experimental error as the liquid a i r . It has also been found that a heated palladium tube, used to analyze a gas mixture containing hydrogen, i s particu-l a r l y adaptable to the analysis method. If the gas contains methane, the temperature to whioh the palladium i s heated should not exceed 325°C. Carbon monoxide in the mixture does not required any limitations with respect to temperature. Carbon monoxide may be oxidized by silver oxide mixed with hopcalite at room temperature. The disadvantages 2 5 . o f t h i s method a r e : o n l y p a r t of the carbon d i o x i d e may be reoovered; the r a t e of r e a c t i o n ' d e c r e a s e s r a p i d l y w i t h the amount of s i l v e r carbonate formed* A c e t y l e n e may be completely removed by condensation at l i q u i d a i r temperature (-l86°C)• 2 6 . PART I I . THE CHEMISORPTION OF WATER BY AN ACTIVATED CARBON I. INTRODUCTION The mechanism of the o x i d a t i o n o f a oarbon s u r f a c e i s extremely complicated because of the heterogeneous n a t u r e of the s u r f a c e . The h e t e r o g e n e i t y m a n i f e s t s i t s e l f i n a l l s t u d i e s o f the su r f a o e ; f o r example the i n i t i a l h i g h heat of a d s o r p t i o n o f oxygen on c h a r c o a l proves beyond doubt t h a t p a r t s of the s u r f a c e are more r e a c t i v e than o t h e r s . S t u d i e s * w i t h which we need not concern o u r s e l v e s here, show t h a t the a c t i v -i t y o f a sample of c h a r o o a l i s e n t i r e l y dependent on i t s p r e -v i o u s h i s t o r y . I t i s t h i s dependence which makes the c o r r e l a -t i o n o f the data from d i f f e r e n t work on the s u b j e c t v e r y d i f f i -c u l t . With r e g a r d to the s u b j e c t d e a l t w i t h here, the chemi-s o r p t i o n o f water vapor by an a c t i v e oarbon, the l i t e r a t u r e i s of a c o n f l i c t i n g n a t u r e 2 1 , and i s t h e r e f o r e v e r y hard to e v a l u a t e . Very l i t t l e of t h i s work has a d i r e c t b e a r i n g on the s u b j e c t c o n t a i n e d h e r e i n , but i t i s w e l l known that char-c o a l r e t a i n s a r e l a t i v e l y g r e a t amount of water vapor a t zero p r e s s u r e 2 2 * 2 ^ » 2 ^ , The purpose of t h i s i n v e s t i g a t i o n was to determine 27. the nature of the r e a c t i o n between the s u r f a c e and water. M c G e e r 1 4 had commenced t h i s work-and h i s r e s u l t s i n d i c a t e d that hydrogen was formed. P r e v i o u s l y McMahon2'5 had performed a s i m i l a r examination u s i n g carbon d i o x i d e as adsorbate and h i s work has been o u t l i n e d i n the i n t r o d u c t o r y n ote. B r o w n i n g 1 0 f o l l o w i n g t h i s up, examined the e f f e c t o f oxygen c o n c e n t r a t i o n on the c o n s t i t u t i o n of the desorbed gases. I t was found t h a t f o r low c o n c e n t r a t i o n s of oxygen (up to .66 micro mols/gm) t h a t o n l y oarbon monoxide c o u l d be re c o v e r e d , at a minimum temperature of 4.50 °C. With h i g h e r c o n c e n t r a t i o n s of oxygen both carbon monoxide and d i o x i d e oould be recove r e d , a t lower temperatures. " T h e ' r a t i o s of the amounts of these two gases i n d i c a t e d t h a t t h e r e was a r e d i s t r i b u t i o n o f the oxygen on the s u r f a c e , a r e s u l t a l s o n o t i c e d b e f o r e by McMahon. These f a c t s i n d i c a t e d t h a t the s u r f a c e complex formed at the lower concen-t r a t i o n s i s much more s t a b l e than the one formed a t the h i g h e r c o n c e n t r a t i o n s . From the r a t e o f oarbon monoxide e v o l u t i o n at 4J>0°C i t was seen t h a t even the s t a b l e complex formed d i d not correspond t o the f o r m a t i o n of s i n g l e Keto g r o u p i n g s 2 ^ . I t would t h e r e f o r e be expected t h a t when the s u r f a c e was o x i d i z e d by water, at a low c o n c e n t r a t i o n t h a t no carbon monoxide would be evolved at low temperatures. The c h a r c o a l used was the same sample used by McMahon. 28. I I . APPARATUS The apparatus was s i m i l a r t o t h a t used p r e v i o u s l y . However i t was e n t i r e l y r e c o n s t r u c t e d because i t had become r a t h e r run down. A few major m o d i f i c a t i o n s were found neces-sary as the work proceeded, and these are f o r t h w i t h d e s c r i b e d . The water p u r i f i c a t i o n apparatus i s g i v e n i n Diagram I I . Water, r e d i s t i l l e d from potassium permanganate, was s e a l e d i n t o the tube B, and most of the d i s s o l v e d gases were removed from i t by e v a c u a t i o n through S 2 . S3 was then c l o s e d and the system outgassed t h o r o u g h l y w i t h h e a t i n g of the w a l l s * S 2 was c l o s e d and the mercury i n A moved up to the cut o f f p o s i t i o n . S3 was opened and a few m i l l i l i t e r s of water were condensed i n t o the l i q u i d a i r t r a p C. S3 was c l o s e d and the condensate was outgassed f o r one hour. The water was l i q u i d a i r d i s t i l l e d from C to D and the e v a c u a t i o n repeated* The f i n a l d i s t i l l a t i o n was performed u s i n g an i o e bath, draw-i n g the vapor phase o f f from time to time through S 2 . -Io t e s t the p u r i t y of the vapor w i t h r e s p e c t t o d i s s o l v e d gases, the mercury i n A was lowered, and then r a i s e d , compressing the vapor, (about one thousand t i m e s ) , i n t o the c a p i l l a r y * The l i q u i d water that was thus formed was pushed to the top of the c a p i l l a r y and examined f o r bubbles of permanent gas* With the d i s t i l l a t i o n procedure f o l l o w e d , no bubbles were found i n d i -c a t i n g t h a t the gas was v e r y pure, assuming t h a t the r a t e of . s o l u t i o n i s low f o r permanent gases d i s s o l v i n g i n water. 29. The p u r i f i e d water vapor was then d i s t i l l e d i n t o the pionometer E from whence i t c o u l d he i n t r o d u c e d i n t o the c h a r c o a l by means of the cut o f f F. The q u a r t z bulb which c o n t a i n e d the c h a r c o a l was the type w i f h a s i d e i n l e t tube. Thus the water had to pass through the c h a r c o a l b e f o r e r e a c h i n g the r e s t of the apparatus. In o r d e r t o examine the gas over the c h a r c o a l a con-densing tube, around which l i q u i d a i r or dry i c e c o u l d be p l a c e d , was s e a l e d i n t o the apparatus above the q u a r t z tube. I n o r d e r t o remove water vapor from the gases drawn o f f the c h a r c o a l a condensing tube was a l s o p l a c e d i n the c o l l e c t i n g system. I n some cases the gad was drawn i n t o the a n a l y s i s gauge without p r i o r removal of the water. To remove t h i s gas i n the a n a l y s i s system a phosphorus pentoxide tube, s e a l e d to the e x t e r n a l volume through a stopcock, was used. The a d s o r p t i o n of hydrogen, oarbon monoxide and aoetylene on the phosphorous pentoxide were measured and found t o be n e g l i g i b l e . The gas a n a l y s i s system has been d e s c r i b e d i n P a r t I . Because i t was d e s i r a b l e to check the a n a l y s i s from time t o time, and to study the a n a l y s i s , g e n e r a t o r s f o r oarbon mon-oxide, hydrogen and aoetylene were set up. The amount of gas c o l l e c t e d was o r i g i n a l l y measured by expanding the gas from the storage bulb i n t o the e x t e r n a l volume of the gauge, then expanding the gas from the e x t e r n a l volume i n t o the a n a l y s i s gauge. From the p r e s s u r e , and the measured volumes the amount of gas c o u l d be c a l c u l a t e d . WATER PURFICATION APPARATUS 3 0 . However, these volumes oould o n l y he measured by the r e v e r s e expansion, and a simple c a l c u l a t i o n shows t h a t i f an e r r o r of + 1 mm. i n 20 cms. i s made i n the pr e s s u r e r e a d i n g the c a l c u -l a t e d volumes w i l l be known to o n l y A c c o r d i n g l y a more ac c u r a t e measure of the gas was d e s i r a b l e . T h i s was accom-p l i s h e d as f o l l o w s : The T r e p l e r pump was m o d i f i e d so t h a t i t c o u l d a l s o be used t o measure the amount of gas c o l l e c t e d . I t was de-sign e d so t h a t a range of 7«33 x 10** 2 t o 246 mioromals oould be a c c u r a t e l y e s t i m a t e d . I t c o n s i s t e d e s s e n t i a l l y o f McLeod gauge w i t h t h r e e d i f f e r e n t r a t i o s , each r a t i o b e i n g used t o measure the pr e s s u r e i n d i f f e r e n t known volumes. The apparatus i s drawn i n Diagram I I . The gas from the c h a r c o a l entered at A and was removed t o the a n a l y s i s gauge at D. The volumes AB, BC', CS, SD were measured i n the accepted manner. C a l i b r a t i o n of Apparatus. Gas A n a l y s i s Gauge. Volume between stopcock and f i r s t mark 09830 c c . " '» " " second " 1385 oc. " of gauge 2 1 6 . 6 oc. Distance between s c r a t c h marks 2 . 5 2 cms. R a t i o s : ( l ) 4 . 5 4 x 1 0 " 4 (2) 6 . 2 7 x 1 0 - 4 Conversion f a c t o r s : ( l ) 1 cm. of Hg = 1 . 2 0 5 omms. at N.T.P, (2) 1 cm. of Hg = 1 .670 " » rt 3 1 . Volume / mm. between marks = 1.49 omm/mm. Change in gauge ratio /cm. = .688 x IO - 4. Volume of gas analysis tips • I . 3 8 7 cos. External Volume • 84.9 cos. Water Picnometer. Radius of capillary = .118 cm. Mioromols of water /mm. at 20°C • 242 mim/mm. Large McLeod Gauge. The calculated calibration values given below were made from "Taddington* s original laboratory notes. The calculations he gave do not agree with his original data. The corrected values given in the diagram are not entirely acceptable because at some time in the last fifteen years the capillary was deformed by heating. T O S S •AMI cut*. « V 7 © 6 C M . \6 Total Volume = 514.3 ccs 32. Toepler Pump. The l e t t e r s i n the data below r e f e r to Diagram I I I . Volume CS .09149 oc. Volume BS ...... 7.696 cc. Volume AS 319.7 cc. Volume SD 149.0 ocs. Volume BD 146.7 ccs. Volume AD 468.7 ccs. R a t i o s : ( l ) A to C = 2.86 x 1 0 ~ 4 (2) B to- C - 1.19 x 10**2 (3) A to B » 2.41 x lO -* 2 Conversion f a c t o r s f o r pressures read at 20°C; Ra t i o Pressure (oms.) No. of mioromols A t o C 1 7*33 x 10" 2 40 2.95 B to C 1 9.55 x 10- 1 40 38.2 A to B 1 6.17 40 246 T o t a l range = 7.33 x 10~ 2 to 246 mioromols. 3 3 I I I . EXPERIMENTAL In t h i s p a r t the r e s u l t s of two separate runs are g i v e n . The f i r s t was of the nature of a p r e l i m i n a r y i n v e s t i -g a t i o n , and the second has completed, up to the p r e s e n t time, the i n v e s t i g a t i o n of the r e a o t i o n between the s u r f a c e and water w i t h r e g a r d to the gases produced a t room temperature, and to the gases evolved when the c h a r c o a l was heated up t o 450°C. (1) PRELIMINARY INVESTIGATION The c h a r c o a l was outgassed f o r 5 8 . 7 5 hours at 1100°C. At the end of t h i s time, and at t h i s temperature* the p r e s s u r e over the c h a r c o a l was 2 x 10"-^ cms. w i t h the pumps running j and 0 x 1 0 - ^ cms. a t room temperature when the c h a r c o a l was cut o f f . The l a r g e MoLeod gauge was c l o s e d o f f from the char-c o a l , and i n the f o l l o w i n g i n t e r v a l of 4 8 days the p r e s s u r e rose from 0 x 10""^ cms. to .5 x l O " ^ cms. i n the gauge, and from 0 x 10""^ cms. to 4.5 x lO"*^ cms. over the c h a r c o a l . The c h a r c o a l was then outgassed a t room temperature and 81.6 mioro-mols/ gm of water vapor were admitted. The i n i t i a l r e a c t i o n was v e r y r a p i d , f o r a f t e r t h r e e hours the p r e s s u r e was un-readable on the l a r g e gauge. A f t e r f i f t e e n hours the gas r e s u l t i n g from the r e a c t i o n was pumped o f f the c h a r c o a l , i t s q u a n t i t y measured, and an a l y z e d . The p r e s s u r e over the char-c o a l , a f t e r two hours of continuous pumping, appeared to be 1.42 x 10"" 3 cms., but t h i s was the same a t a l l p o i n t s i n the c a p i l l a r y tube of the gauge, and hence was due t o water. The c h a r c o a l was c l o s e d o f f , and the p r e s s u r e above i t re a d .at v a r i o u s times. Table I g i v e s these r e a d i n g s which are p l o t t e d i n Graph I . Table I . Time (hrs.) P r e s s u r e (cms x 10 4) 0 *142 15 11.7 39 21.1 111 29.1 157 32.0 From these f i g u r e s i t i s seen t h a t the r e a c t i o n i s proce e d i n g w i t h a d e f i n i t e v e l o c i t y . With carbon d i o x i d e as adsorbate, McMahon showed t h a t a constant p r e s s u r e was a t t a i n e d a f t e r an hour or so. Comparison of the times r e q u i r e d to reach e q u i l i b r i u m f o r oarbon d i o x i d e and water as adsorbate shows t h a t the o x i d a t i o n of the- s u r f a c e by water proceeds w i t h a muoh lower r a t e than the r e a c t i o n w i t h carbon d i o x i d e , even i n view of the f a o t t h a t the water vapor was presen t i n such a q u a n t i t y t h a t the s u r f a c e was s a t u r a t e d . In a l l , f o u r separate samples of gas were drawn o f f the c h a r c o a l and an a l y z e d . Table I f * shows the r e l a t i o n between the p r e s s u r e over the c h a r c o a l and the amount taken o f f . Table I I I g i v e s the r e s u l t s of the a n a l y s i s . A See page 41. § See page 41. 3 5 . Samples 1 and 2 c o n t a i n e d a c o n s t i t u e n t which was condensable. The percentages g i v e n are those e x c l u s i v e of t h i s component. T h i s i s done because the condensable p o r t i o n was, very p r o b a b l y water vapor. T h i s i s borne out by the f o l l o w i n g f a c t s : water vapor was n o t i c e d i n the T o e p l e r pump; the f r a c -t i o n o f the gas condensed by l i q u i d a i r v a r i e d between 5 per cent f o r the f i r s t p o r t i o n s of a sample to 0 per cent f o r the l a s t ones whereby a l l the readings were i n c o n s i s t e n t . I t can be seen from the a n a l y s i s t a b l e d t h i s way t h a t the r e a d i n g s are f a i r l y c l o s e t o g e t h e r . Because ,the r e a d i n g s f o r sample 4 are about the same when the condensable p a r t i s i n c l u d e d i t i s i n c o r p o r a t e d i n t o the t a b l e . A comparison of Table I I I above and Table I I of McGeer*s t h e s i s 1 ^ shows a complete l a c k of agreement* I n c o n s i d e r i n g the q u a n t i t i e s of gas which were a n a l y z e d i n h i s work i t may be seen t h a t they r e p r e s e n t a p r e s s u r e of 1 t o 8 cms. on the a n a l y s i s gauge. Because no p r o v i s i o n was made f o r the removal of water vapor, which was c e r t a i n l y p r e s e n t , t h i s would c o n t r i b u t e a p a r t i a l p r e s s u r e of up t o 2 cras.j depending on the amount absorbed by the w a l l s of the gauge. I t t h e r e f o r e seems p o s s i b l e to a t t r i b u t e the condensable p a r t i n h i s a n a l y s i s to the presence of water.-Sample 4 appears to be anomalous i n both Table I I I and Table IV. I n the former Table i t i s seen t h a t .338 micro-mols of t h i s gas were obtained from a p r e s s u r e above the ohar-c o a l of o n l y 2.3 x 10 cms. which i s o e r t a i n l y not i n agree-ment w i t h the other f i g u r e s . I n Table IV, sample 4 i s shown 36. to c o n t a i n a two carbon gas, by o x i d a t i o n on the copper oxide; i t was the o n l y sample i n a l l of the work t h a t i n d i c a t e d t h i s . T h i s was not a c e t y l e n e because l i q u i d a i r was kept on the t i p d u r i n g o x i d a t i o n . I t does not seem l i k e l y t h a t any condensable gases were g i v e n o f f by the heated q u a r t z tube, because t h i s a c t i o n was immediately t e s t e d f o r and found not to occu r . Sample 4 remains somewhat a dilemna. The r e s u l t s of t h i s p r e l i m i n a r y work showed without doubt t h a t almost pure hydrogen was formed a t room temperature, and t h a t no carbon monoxide c o u l d be o b t a i n e d a t t h i s tempera-t u r e . They show a l s o a d e f i n i t e r e l a t i o n between the amount of water on the s u r f a c e and the v e l o c i t y o f the r e a c t i o n . Reference t o Table I I bears t h i s out. When a h i g h concentra-t i o n of water was p r e s e n t , i n 13 hours .338 mioromols/gm were formed, but when most of the water was removed (when the f i r s t sample was withdrawn) o n l y .055 mioromols formed i n 157 hours. The p r e l i m i n a r y work a l s o i n d i c a t e d t h a t the water should be removed from the gases b e f o r e a n a l y s i s . In order to accomplish t h i s l i q u i d a i r t r a p s were s e a l e d in.to the char-c o a l system and the d i f f u s i o n pump c o l l e c t i n g system. (2) SECOND RUN (a) The F i r s t Admission of Water. The c h a r c o a l was outgassed f o r 100 hours a t tempera-t u r e s v a r y i n g between 1000°C and 1100°C. An i n t e r e s t i n g p o i n t w i t h r e g a r d t o t h i s method of a c t i v a t i o n may be mentioned here. MoMahon 2^ showed t h a t as the temperature of the c h a r c o a l i s 37. increased, the oxygen on the surface redistributes i t s e l f to form a more stable complex. In view of this fact i t would appear that the quickest method of removing the oxygen from the surface, whioh content i s presumably the criterion of the state of activity, would be to outgas the charcoal at the relatively low temperature of j>00°C to 600°C for some time before resorting to high temperature evacuation. After standing for 145 hours at room temperature the pressure over the charcoal rose to .6 x 1Q"*3 oms. The charooal was then outgassed to zero pressure at room tempera-ture and 21.8 mioromols/gm. of water were admitted to i t . An immediate reaction was observed; the mercury in the cut off between the charcoal and the picnometer was placed in such a position that when a slight increase in the pressure, above the charcoal, over the vapor pressure of water, in the pic-nometer, occurred the gases would bubble through the mercury -> in the cut off. During the f i r s t few moments the reaction appeared to be quite violent. The pressure which subsequently developed over the charcoal was not measured for twelve hours -and after this period i t was too high to read on the-large gauge. li q u i d air was placed on the trap directly above the charcoal and a brown substance condensed out of the gas phase. The pressure over the charcoal did not seem to be affected by the liquid a i r . When the liq u i d a i r was removed the brown condensate evaporated, but not u n t i l the temperature of the glass had risen to a value muoh higher than -l86°C. The gas which resulted from the reaction was in-38. v e s t i g a t e d i n the f o l l o w i n g manner. Twenty three hours a f t e r the water had heen i n t r o d u c e d i n t o the c h a r c o a l , the f i r s t sample was drawn o f f j (hut notthrough l i q u i d a i r ) u n t i l the pr e s s u r e over the c h a r c o a l had reached a zero v a l u e . While t h i s sample was b e i n g a n a l y z e d the p r e s s u r e over the c h a r c o a l rose s t e a d i l y , because of the water s t i l l on the s u r f a c e . A f t e r e i g h t y seven hours t h i s reached a va l u e o f 6.8 x 10"*4" cms. T h i s sample was then drawn o f f w i t h l i q u i d a i r on the t r a p i n the d i f f u s i o n pump c o l l e c t i n g system. T h i s prooedure separated the sample i n t o two p a r t s , which are l a b e l l e d samples 3 and 4. The r e s u l t s of these r e a d i n g s f o r the amounts taken o f f are shown i n Table I V A . The r i s e i n p r e s s u r e over the c h a r c o a l a f t e r each sample was drawn o f f are l i s t e d i n Table V^, and are p l o t t e d on Graph I . I t i s seen from Table V - B t h a t a f t e r about f o r t y days the p r e s s u r e rose t o o n l y 4.1 x 10" 4 , cms. Because t h i s would y i e l d a sample too s m a l l f o r a n a l y s i s i t was kept over the c h a r c o a l when the second admission o f water was made. The r e s u l t s of the a n a l y s i s of samples 1 and 2 are shown i n Table Vl^f The i n v e s t i g a t i o n o f the condensable p o r t i o n i s noted l a t e r . I t was noted above t h a t sample 1 was not taken out through l i q u i d a i r . The f i g u r e s f o r the a n a l y s i s of t h i s A See page 42 § See page 42 See page 42 39. sample are the percentages found a f t e r the condensable p o r t i o n had been removed by condensation o f l i q u i d a i r i n the a n a l y s i s gauge. However, an important p o i n t a r i s e s here* The f o u r p o r t i o n s o f sample 1 an a l y z e d were passed over the phosphorous pentoxide i n the e x t e r n a l volume of the a n a l y s i s gauge I n order to remove the water which was p r e s e n t . I n order t o t e s t the gas f o r the complete removal o f water vapor each p o r t i o n was admitted t o the gauge and oompressed i n t o the c a p i l l a r y , and p r e s s u r e s r e a d a t v a r i o u s p o i n t s t h e r e i n . The product o f pr e s s u r e times volume remained s e n s i b l y constant, showing the absence o f a v a p o r - l i q u i d e q u i l i b r i u m . T h i s does not r u l e out the p o s s i b i l i t y t h a t t h e r e was water remaining i n the gas phase o n l y i n the c a p i l l a r y . Because the a n a l y s i s of each p o r t i o n of sample 1 are r e a s o n a b l y c o n s i s t e n t when based oh the unoondensable p a r t o n l y they are t a b u l a t e d t h i s way. T h i s t a b u l a t i o n then n e g l e c t s the. brown condensate noted above* but i n the absence of anything b e t t e r t o assume, i t i s taken that the condensable p o r t i o n i n sample 1 was water vapor. The percentages i n Table VI under " o x i d i z a b l e " are the r e s u l t of the treatment o f the r e s i d u e w i t h hot copper oxide and condensation of the r e s u l t a n t gas i f f the l i q u i d a i r tube. Approximately equal volumes of GOj, were found as the volumes of gas which disappeared. T h i s may have been a p u r e l y f o r -t u i t o u s r e l a t i o n s h i p s i n c e some carbon d i o x i d e may have come from the p i c e n e . In any case, the p o s t u l a t i o n of t h i s as the source of the carbon d i o x i d e i s more i n v i t i n g than a t t r i b u t i n g i t r to oarbon monoxide from the c h a r c o a l . There was no 40. a b s o r p t i o n of any p a r t of sample 2 by the phosphorous pent-oxide. The i n v e s t i g a t i o n of sample 3 w i l l be d e s o r i b e d l a t e r . (b) The Second Admission of Water Vapor. I t has been s t a t e d above t h a t a f t e r 1 0 7 7 hours the pre s s u r e above the c h a r c o a l had r i s e n , t o o n l y 4 . 1 x 1 0 ~ 4 cms. I t was not deemed worthwhile t o analyze t h i s p o r t i o n . To f i n d i f any f u r t h e r r e a c t i o n would occur between the s u r f a c e and the water 1 4 . 5 mioromols /gm. were admitted t o the c h a r c o a l . In twelve hours the p r e s s u r e had become unreadably h i g h and bef o r e the f i r s t sample of gas was drawn o f f 3 8 1 hours were allowed to e l a p s e . When l i q u i d a i r was put on the t r a p above the c h a r c o a l o h l y a white condensate of water appeared, masking the brown, i f any. The gas was drawn o f f i n t h r e e samples, as b e f o r e , but a l l t h r e e were allowed t o pass through the l i q u i d a i r . t r a p I n the c o l l e c t i n g system. The re a d i n g s f o r the amounts c o l l e c t e d i n each oase are g i v e n i n Table VIl£ The r e s u l t s of the a n a l y s i s o f these samples are t a b u l a t e d i n Table VIII#. A f t e r sample 3 had been taken out the pressure, d i d not r i s e i n th r e e days. The c h a r c o a l was evacuated by means of the d i f f u s i o n pump and T e o p l e r pump, w i t h l i q u i d a i r on-the t r a p f o r f i f t e e n hours. T h i s was done t o remove the water vapor and the brown condensate. The i n v e s t i g a t i o n of t h i s condensed m a t e r i a l i s g i v e n below. A See page 4 3 . f See page 4 3 . 41. Table I I . Sample Amount of Gas Ho. Taken O f f (Mioromols/gm) P r e s s u r e over c h a r c o a l when sampling s t a r t e d (cms, x 10 4 ) Time taken between samples (hrs) 1 2 .338 .055 unreadable (High) 32 15 157 .008 6 52 4 .338 2.3 74 A Sample too s m a l l f o r a n a l y s i s . Table I I I . Sample Amount of Gas A n a l y s i s (S t>y Volume) no. Analyzed H 2 Residue Condensable Two Carbon (cmms) i 15 91.5 8.5 0 19 .8 99.4 .6 0 13.1 99.1 .9 0 10.6 100. 0 0 13.1 96 4.0 0 2 8.74 98.7 1.3 0 7.0 100 0 0 5.7 97.2 3.8 0 4 16.3 75.5 1.48 17.05 6.3 12.1 75.2 .99 16*3 6.43 14 .6 77'0 .82 17.4 4.95 42. Table IV. Sample Amount of Sample P r e s s u r e over C h a r c o a l Time between Ho. Mioromols/gm. when sample taken t a k i n g of Samples (hrs) 1 . 6 2 unreadable (High) 2 . 0 3 ( 6 . 8 x 1 0 ^ 4 cms. 3 . 0 9 8 ( 6 . 8 x 10 **4 cms. A. A f t e r Sample 1 . Time(hrs.) P r e s s u r e (8ms x 10 4) 0 . 0 3 14 . 2 5 2 . 7 2 2 i 0 3 . 7 4 8 . 3 5 . 0 5 8 . 1 5 5 . 6 9 6 . 5 6 . 8 Table V. B. A f t e r Samples 2 and 3 , Time(hrs) P r e s s u r e 0 0 2 0 . 1 . 7 7 141 . 0 3 . 0 1 0 7 7 4 . 1 Table VI. Sample Amount of Gas A n a l y s i s (% by Volume) Ho. Analyzed Hg Condensable O x i d i z a b l e Residue omms. M.T.P. 1 4 5 . 0 9 7 . 9 1 . 2 5 . 8 5 • 2 1 . 7 9 8 . 3 - 1 . 3 5 . 4 21 .7 - 9 8 . 1 - 1 . 0 4 . 9 8 . 8 9 8 . 2 - • 0 1 . 8 2 5 . 6 9 3 . 3 0 6 . 4 . 3 5 . 7 5 9 0.0 0 9 . 8 . 2 42. Table V I I . Sample Amount of Sample P r e s s u r e over C h a r c o a l Time between Ho. Micromols/gm. when Sample taken t a k i n g o f Samples 1 1.01 unreadable (High) 281 2 .245 " " 125 2 .015 4.8 x 10" 4 739 Table V I I I . Sample Amount of Gas A n a l y s i s (f. by Volume) No. Analyzed Hg O x i d i z a b l e Residue omms. N.T.P. : 55 99.8 0 .2 52 99.8 0 *2 52 99.6 0 .4 18 99.2 0 .7 15 99.4 0 .6 18 99.4 0 .6 14 9ea 1.8 .1 7 92% 0 8 44. (c) Examination of the Condensable P o r t i o n . Reference above has been made to a "condensable por-t i o n " from time to time. I t i s termed t h i s f o r l a c k of a n y t h i n g b e t t e r to c a l l i t and the i n v e s t i g a t i o n of i t turne d out t o be one of the most i n t e r e s t i n g , but the l e a s t f r u i t f u l , p a r t s of t h i s work. I t was s t a t e d t h a t a f t e r the f i r s t admission t o the c h a r c o a l had been made, l i q u i d a i r was p l a c e d on the tube above the c h a r c o a l and a brown r e s i d u e s e t t l e d out, which s l o w l y disappeared when the l i q u i d a i r was removed. T h e r e f o r e , sample 1 of Table IV presumably c o n t a i n e d t h i s substance. I t was a l s o s t a t e d t h a t sample 1 was passed over phosphorous pentoxide. I t was then found, w i t h one of the p o r t i o n s ana-l y z e d t h a t when a f t e r a l e n g t h of time (20 mins.) over the phosphorous pentoxide the p r e s s u r e of the sample dropped from 7.1 to J5.1 cms. on the a n a l y s i s gauge, and t h a t no f u r t h e r c o n t r a c t i o n o c c u r r e d when the gas was l e f t over the pentoxide f o r another twenty minutes. Hone of t h i s condensed i n l i q u i d a i r , the remainder was hydrogen; because o f the decrease of 2 cms, the vapor p r e s s u r e of water, i t was assumed t h a t t h i s was merely water vapor. Meanwhile, the p r e s s u r e over the c h a r c o a l had r i s e n t o 6.8 x 10~ 4 oms. (see Tab l e I V ) . Again l i q u i d a i r was put on the tube above the c h a r c o a l and the brown substance s e t t l e d out. The p r e s s u r e remained a t 6.8 x 10~ 4 cms., which i n d i c a t e d t h a t the vapor p r e s s u r e of the substance over the c h a r c o a l was v e r y low, or t h a t i t was condensing i n the l a r g e gauge when r e a d i n g s were taken. To>-check the l a t t e r a l t e r n a t i v e , s o l i d carbon d i o x i d e was p l a c e d 4 5 . on the same tube, Ho brown r e s i d u e s e t t l e d out a f t e r one hour, t h e r e f o r e , the f i r s t a l t e r n a t i v e was assumed. The next samples taken o f f the c h a r c o a l (samples 2 and 3 , Table IV, were taken o f f through l i q u i d a i r , thus sample 3 , which d e f i n i t e l y c o n t a i n e d the brown substance ( i t c o u l d be seen i n the l i q u i d a i r t r a p i n the c o l l e c t i n g system) was separated from sample 2 , Sample 2 was run over the phos-phorous pentoxide f o r 20 minutes, but no decrease o f p r e s s u r e was observed. T h e r e f o r e , whatever the phosphorous pentoxide was a b s o r b i n g was i n the condensable p o r t i o n , whioh i s obvious-l y what one would expect i f i t was water vapor. I t s t i l l r e -mains to be p o i n t e d out t h a t i n a l l the times water vapor has been condensed, i t has always appeared white, not brown. Yet, i t may appear brown i f o n l y a very s m a l l q u a n t i t y i s p r e s e n t , due t o the simultaneous condensation of mercury. The conden-sate, sample 3 , was outgassed u n t i l no d i s o h a r g e appeared above i t . I t was then pumped i n t o the storage bulb* and ex-panded i n t o the a n a l y s i s gauge. The r e a d i n g s were as f o l l o w s : P r e s s u r e o f gas = 5*5 cms. '» II n » 3 , 4 « (over P ^ 10 minutes) » it n _ 3 #Q « (condense In l i q u i d a i r ) » " " • . 2 " (heat palladium) A l l of the gas should have condensed i n the l i q u i d a i r . The p o s s i b i l i t i e s were: (a) The c o l l e c t i n g system was l e a k i n g - but i t d i d n ' t l e a k b e f o r e and no s i g n o f a l e a k appeared a f t e r . A l s o , the c o n t r a c t i o n noted when the p a l l a d i u m was heated c o u l d not have been o b t a i n e d w i t h a i r . 46. (b) Some unoondensable gas was s t i l l p r e s e n t i n the c o l l e c t i n g system - but i t was outgassed when condensed. (o) On s t a n d i n g the condensable p o r t i o n decomposes when not absorbed by the c h a r c o a l . (d) The condensable p o r t i o n r e a c t s w i t h phosphorous pentoxide to g i v e hydrogen. The next p o r t i o n of sample 3 was t e s t e d to see i f • some p a r t of i t condensed i n t h e - a n a l y s i s gauge when compres-s i o n occurred* P r e s s u r e s were read at v a r i o u s volumes, and i t was found t h a t some gas was condensing. These r e a d i n g s make i t p o s s i b l e to c a l c u l a t e the vapor p r e s s u r e of the gas conden-s i n g and i t was found t o be 2.6, 2.15, and 2.9 cms. W i t h i n the l i m i t of e r r o r of sueh a c a l c u l a t i o n t h i s i s the vapor p r e s s u r e of water. Many more r e a d i n g s of" d i f f e r e n t types were taken i n an attempt t o o b t a i n more p r o p e r t i e s of t h i s condensable p o r t i o n , but they were c o n s i s t e n t l y i n c o n s i s t e n t , and are not i n c l u d e d . However, one more f a c t should be i n c l u d e d . The, d i f f u s i o n pump c o l l e c t i n g system i n whioh the condensable p o r t i o n from the second admission had been f r o z e n out, was outgassed at h i g h vacuum f o r twelve hours, through the mechan-i c a l pump. A f t e r t h i s time l i q u i d a i r was a g a i n put on the t r a p , and the brown r e s i d u e s e t t l e d out a g a i n . I t was d e f i n -i t e l y on the i n s i d e of the tube. I t i s hard t o admit t h a t such a gre a t d e a l o f time was spent p r o v i n g the, presence of water i n the gas, i n f a c t a great many t h i n g s are not c o n s i s t e n t w i t h the view t h a t the 47.. condensable portion was only water. The question i s l e f t open. (3) THE GASES EVOLVED AT ELEVATED TEMPERATURES. At the present time the charcoal has been heated up to 450° in two steps. The f i r B t was at 240° and the second at 450°. The results of the analysis indicates that no carbon monoxide i s being given off the charcoal up to 450°. It i s not proposed to report the results obtained for this u n t i l later when a complete investigation w i l l be given as an adden-dum to this thesis. IV. DISCUSSION The results obtained show that a chemical reaction takes place between the water and the surface. Prom the anal-ysis of the gases produced hydrogen i s found to be present in amounts from 99 to 100 percent; therefore, the overall effect of the reaction must be the oxidation of the surface. McGeer 1 4 showed that the gases found according to his analysis could be accounted for by assuming the presence of metal carbides i n the charcoal, formed by traces of metals and carbon during the activation. The attainment of equilibrium, and the analysis, shows that i f any carbides are in the charcoal they are present in such small amounts that their effect i s negligible. Graph I shows that the reaction i s proceeding toward equilibrium, the exact nature at which can not be stated here. 48. F o r the r e a c t i o n s : H 2 0(g) + C = CO + H 2, 2 H 2 0(g) + C » C 0 2 + 2 H 2 , A F M y » +21,826 and +19 ,645 c a l o r i e s 6 , and t h e r e f o r e these simple r e a c t i o n s do not r e p r e s e n t the one which i s t a k i n g p l a c e here. Graph I shows t h a t when the concentra-t i o n of the water i s decreased by drawing the gases o f f the c h a r c o a l , the r a t e of r e a c t i o n i s a l s o decreased. From the measurements made no c a l c u l a t i o n of the amount of water l e f t on the c h a r c o a l can he made, f o r although the amount of water put on i s r o u g h l y known, the amount taken o f f oan not he even approximately estimated. In any case the water i s adsorbed and hydrogen i s formed. At t h i s temperature, and w i t h a c t i v e carbon, the nature of the complex formed i s not known, but i t i s found t h a t the o x i d a t i o n of oarbon by water at temperatures from 700°C to 1200°C occurs w i t h the f o r m a t i o n of Keto groups, from whioh carbon monoxide desorbs through i n t e r m e d i a t e ketene g r o u p s 2 7 . The extent to whioh the water w i l l o x i d i z e the s u r -f a c e has not been measured. I n order to have o b t a i n e d t h i s i n f o r m a t i o n more water should have been put on a f t e r the gases from the second admission had been f i n a l l y pumped o f f . T h i s w i l l be i n v e s t i g a t e d l a t e r . The a n a l y s i s of the gases shows a s m a l l r e s i d u e i n a l l oases. At one p o i n t , when a p a r t i c u l a r l y l a r g e sample was a v a i l a b l e , i t was found p o s s i b l e to c o l l e o t one c e n t i m e t e r of t h i s r e s i d u e i n the a n a l y s i s gauge, by p u t t i n g a l a r g e p o r t i o n of the sample i n t o the gauge and a l l o w i n g the hydrogen to d i f f u s e out. The gas was q u i t e i n e r t and was taken to be 49. n i t r o g e n i n t r o d u c e d w i t h the water. There was a p o s s i b i l i t y t h a t the warm oxides of mer-cury i n the d i f f u s i o n pump c o l l e c t i n g system would o x i d i z e the hydrogen when i t was pumped o f f the c h a r c o a l . Such a r e a c t i o n would be o b v i o u s l y u n d e s i r a b l e . . In order t o f i n d out i f i t o c c u r r e d a known amount of hydrogen was p l a c e d i n the system and the d i f f u s i o n pumps s t a r t e d . A f t e r one h a l f hour the hydrogen was pumped i n t o the T o e p l e r pump and i t was found t h a t none had disappeared* showing t h a t the method of c o l l e c -t i n g the hydrogen r e s u l t e d i n no l o s s . V. SUMMARY Water w i l l o x i d i z e the s u r f a c e of an a c t i v a t e d carbon at room temperature to produce a t l e a s t 1.92 miororaols /gm. of hydrogen. An e q u i l i b r i u m i s e s t a b l i s h e d between the-water, hydrogen and the s u r f a c e , a f t e r r e l a t i v e l y l o n g p e r i o d s of time. The nature of the s u r f a c e complex formed i s not i n d i c a t e d . 50 BIBLIOGRAPHY 1. (a) Hartridge, Jour. Sci.Inst. 16, 322 (1939) (Review). (b) Belcher and Spooner, Iron and Coals Trade Review, 148, 165 (1944) (Review). (c) Nash, Ind. Eng. Chem. Anal. Ed. 18, 505 (1946). (d) Price and Woods, Analyst, 69, 117 (1944). (e) Spence, J.C.S., 1302 (1940). 2. Constabaris, Thesis U.B.C. (1945). 3. Smithies, "Gases and Metals" John Wiley and Sons (1937). 4. Berkman, Morrel and Egloff, "Catalysis" p.402, Reinhold Pub. Co. (1940). 3. Fleiger, Ind. Eng. Chem. Anal.Ed., 10, 544 (1938). 6. Wagman, et.al., Jour. Nat. Bur. Standards, 34, 143 (1945). 7. Taylor and McKinney, J.A.C.S., 53, 3604 (1931). 8. Branford and Baldwin, J.C.S., 27 (1942). 9. Arneil, J. Soc. Chem. Ind., 897, 53 (1934). 10. Browning, Thesis, U.B.C. (1942). 11. Cuilleron, Chimie, et Ind. 52, 130 (1944). 12. Blacet et.al., Ind. Eng. Chem. Anal. Ed. 5, 272 (1933). 13. McCullough et.al., Ibid. 19, 999 (1947). 14. MoGeer, Thesis U.B.C, (1946). 15. Burbo, J. Phys. Chem. (U.S.S.R.), 18, 253 (1944). 16* Morikawa et.al., J.A.C.S., 58, 1445 (1936). 17. Pieser and Pieser, "Organic Chemistry", Heath P.192 (1944). 51. 18* Gilman and Brown, J.A.C.S. 52, 4480 (1930). 19. Thompson, Ind. Eng. Chem., 21, 389 (1929). 20. Hammond and Withrow, Ind. Eng* Chem., 25, 653 (1112) (1933). 21. Dietz, "Bibliography of Solid Adsorbents", Hat. Bur. Stan-dards Research Project. Entries 348, to 388. (1944). 22* Courty, Comptes Rendues, 216, 769 (1943). 23. Burrage, J. Phys. Chem. 37, 1095 (1933). 24. Ockrent, J.C.S., 291 (1934). 25. MoMahon, Thesis U.B.C. (1937). 26. Marshall and Browning, Unpublished Results. 27. Sihvonen et.al. Chem. Zentr., II 1474 (1941) (C.A. 38 48573 1944).
Thesis/Dissertation
eng
Chemistry
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Graduate
Part I - Studies in the microanalysis of gases. Part II - The chemisorption of water by an activated carbon
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