Question

What is the pH of a solution that is 0.50 M in sodium acetate and 0.75 M in acetic acid?

Answer 1

4,57

Explanation:

this is an acid tampon solution.
`pH = pKa + log ((Cs)/(Ca))` = 4,75 + log(0,5/0,75) =4,75 +log 0,66 = 4,57 #
pKa is the logarithm (changed of sign) of the dissociation constant of acetic acid; Cs the concentration of the salt (sodium acetate) ; Ca the concentration of the acid (acetic acid). As you can see pH doesn't change with concetration, and change very little changing the amount of salt and of acid