Section 58. Hydrolysis of Sodium Acetate. 



147 



if the total quantity of sodium hydroxide in a solution of it were trans- 

 formed into sodium acetate. Assuming now for the moment that the 

 degree of ionization of each of the two substances in a mixture of them is 

 substantially the same as if it were present alone at the same total concen- 

 tration, it is evident that the ratio of the observed decrease in specific con- 

 ductance produced by the addition of the acetic acid to this calculated dif- 

 ference in the specific conductances of the two substances is equal to the 

 degree of hydrolysis of the salt or to the proportion of it that exists in 

 the state of hydroxide ; provided, of course, the addition of acid has been 

 sufficient to reduce the hydrolysis to appreciably zero. That the actual 

 ionization relations are in fact those just assumed will be evident from 

 the following considerations. Since the hydrolysis is small, the concentra- 

 tion of the sodium acetate will not be greatly changed when the hydroxide 

 is converted to acetate, and, therefore, the new sodium acetate will have a 

 degree of ionization and equivalent conductance substantially equal to that 

 of the main quantity of the salt. Moreover, even though the hydroxide 

 exists in the presence of a much larger proportion of the acetate, its degree 

 of ionization and equivalent conductance will have that value which it 

 would have if it were present alone in water at a concentration approxi- 

 mately equal to the concentration of the acetate, in virtue of the principle 

 that, in a mixture of two largely and nearly equally ionized electrolytes, 

 each has that degree of ionization which it has when present alone at a 

 concentration equal to the sum of the concentrations of the two electro- 

 lytes.* 



The following table contains the results of the calculation of the hydrol- 

 ysis and also the data upon which it is based. The values given in the 

 third and sixth columns are taken directly from table 44. Those in the 

 fourth were obtained by interpolating graphically the equivalent conduct- 

 ance of sodium hydroxide from the results of Noyes and Kato and multi- 

 plying it by the concentration given in the second column. 



Table 45. Hydrolysis of sodium acetate. 



*See Noyes, Congress of Arts and Science, St. Louis Exposition, 4, 318 (1904) ; 

 Science, 20, 577-87 (1904); Technology Quart., 17, 301 (1904). 



