﻿532 Dr. T. Ewan on the Rate of Oxidation 



as the sum of the pressures of oxygen (b — x), aldehyde p 2 , 

 acetic-acid vapour m, and nitrogen N, viz. : — 



P = (7,-,£)+^ 2 + 7tt + N. 

 Substituting the value of^ 2 j us t found, we get 



From this equation x (the diminution in the oxygen 

 pressure) may be obtained when kf is known. The analysis 

 of the gas at the end of an experiment gives a direct deter- 

 mination of x from which k' may be found. The expression 

 is unfortunately a quadratic in x, and is best solved by 

 successive approximations, which, however, makes the calcu- 

 lations somewhat laborious. 



The connexion between the velocity with which oxygen 

 and aldehyde-vapour unite to form acetic acid and the con- 

 centration of the gases (or their partial pressures, which are 

 proportional to the concentrations) is expressed by the 

 equation 



-|i = K. VK-ft- (5) 



p^the partial pressure of the oxygen, p 2 that of the aldehyde. 



— -~ is the rate at which the pressure of the oxygen 



diminishes. 



To integrate this equation substitute (from equation 4) 



a — 2x 

 P2 ~ l + k'{x-m)' 

 p=(b-x), 



and 



This gives 



_ dpi __ dx 

 ~dt~dt 



dx tt n a / a — 2x \ 



After performing the integration this becomes 



n v (2b-a\ 

 2kJ m -k'a-2, ( h -*>-\TT-) 



K*= ' " log- 



+ #(&-#)* + const. . (5 a) 



