CATALYSIS. 33 



Cw = Q, the velocity of the ester formation is expressed by the formula 

 Vl = ki C A C s ; afterward it is expressed by the difference viV2 or 

 ki'C A 'C s k2'C E 'C w . Of the two reaction velocities v\ and V2 at the 

 begining v\ always diminishes while V2 increases. When k\ -C A 'C S = 

 k2-C E 'C w is attained, then the, velocity of both reactions is the same; 

 no measurable decomposition occurs and the system is in equilibrium. 

 The equilibrium condition is the same irrespective of whether we start 

 from alcohol + acetic acid or from the corresponding quantity of acetic 

 ether + water. On equilibrium it is 



or 



K is called the equilibrium constant; as is apparent it can be determined 

 in two ways either from the concentration of the reacting bodies when 

 equilibrium is present or from the velocity coefficient ki and 2 as deter- 

 mined in a manner given below. 



In the above-mentioned transformation of alcohol and acetic acid 

 these two bodies are simultaneously used up. The reaction is therefore 

 called bimolecular, and a reaction is called mono-, bi-, tri-, etc., molecular 

 according to the number of the kinds of molecules which diminish their 

 concentration thereby. 1 



BERZELIUS 2 found that certain bodies by their mere presence, and 

 not by their affinity, have the power of awakening the dormant affinity 

 at a certain temperature, i.e., the power of starting a reaction. These 

 phenomena were called catalytic by BERZELIUS. 



According to OSTWALD S catalysis is the acceleration (or retardation) 

 of a slow-proceeding chemical change by the presence of a foreign body. 

 That body which influences a reaction in this manner is called a catalyst. 

 It does not itself undergo any appreciable change by the reaction. 



Catalytic reactions have been studied, especially by WiLHELMY. 4 

 VAN'T HOFF, S OSTWALD, S ARRHENIUS 7 and BREDIG. S Of all other sub- 

 stances the acids and alkalies seem to act most catalytic. A well-known 



l lt is assumed here that of every kind of molecule one molecule of each takes 

 part in the reaction. 



2 Berzelius, Arsberattelse om framstegen i Fysik och Kemi., 13, p. 245 (1836). 



3 Lehrb. d. allg. chem. 2. Aufl. II., 1, 515. 



4 Poggendorff's Ann., 81, 413 (1850). 



5 Etudes de dynam. chim. (1884). 



6 Lehrb. d. allg. Chem., 2. Auf. II, 2, 199. 



7 Zeitschr. f. physik. Chem., 4, 226 (1889). 



8 Anorganische Fermente (1901); Bioch. Zeitschr., 6, 283 (1907). 



