T.E.P.P. (Tetraethyl pyrophosphate) 
T.E.P.P. is soluble in water. At concentrations normally employed, 
hydrolysis is of the first order provided pH is constant or on the acid 
side. 
sd. leis & -« 2,303 1osi0 a 
t an-X t a-xX 

Since hydrolysis is not appreciably catalysed by hydrogen ions, at 25°C, 
k reduces to: 
k=160[OH7~] + 1.6 x 107? ste 
For convenience, the rate of hydrolysis in terms of the time for 50% 
decomposition is expressed: 
_ loge 2 = 0.693 
Cs50% k k 

(DuBois, 1957). 
133 
