Question

If a buffer solution is 0.130 M 0.130 M in a weak acid ( K a = 1.4 × 10 − 5 ) Ka=1.4×10−5) and 0.540 M 0.540 M in its conjugate base, what is the pH ?

Answer 1

Answer: pH= 0.68015

Explanation:

From the question,

pKa= 1.5×10-5, [salt]= 0.54M, [ acid]=0.13M

Using the Henderson Hasselbalch equation

pH= pKa + log[salt/acid]

pH=1.4×10-4+ log[0.54/0.14]

pH= 0.000015+ 0.618

pH=0.68015