Question

What is the pH of a 75.0 mL solution that is 0.045 M in weak base and 0.053 M in the conjugate weak acid

Answer 1

7.07

Step-by-step explanation:

HA = weak acid = 0.053

A+ = conjugate base = 0.045

Ka = 7.2x10^-8

Ka = [H+][A-]/HA

7 2x10^-8 = [H+][0.045]/0.053

[H+] = 7.2x10^-8 x 0.053/0.045

= 8.48x10^-8

PH = -log[H+]

= -log[8.48x10^-8]

PH = -[login.48 + log10^-8]

PH = -0.928 - (-8)log10

= 7.07