Question

Calculate the pH of a buffer that is 0.012 M C₆H₅COOH ( Ka= 6.3x10-5 ) and 0.033 M NaC₆H₅COO.

Answer 1

Solution

pH=pKa+log$\frac{[A^-]}{[HA]}$

pKa=-logKa=-log($6.3\times10^{-5})=4.20$

[A^-]=0.033M

[HA]=0.012M

pH=4.20+log$(\frac{0.033}{0.012})$

pH= 4.639

pH=4.64