MEDIUMMCQ SINGLEJEE Advanced ChemistryPhysical ChemistryIonic equilibriumBuffer Solutions
What is the pH of a buffer solution which is 0.250 M in benzoic acid, C6H5COOH, and 0.150 M in sodium benzoate, C6H5COONa, if a K for benzoic acid is 6.5 × 10–5 ?
A.3.40
B.3.97✓ Correct
C.4.19
D.4.41
Explanation
6 5 6 5 C H COOH + C H COONa forms acidic Buffer. Thus, 6 5 a 6 5 C H COO pH = pK log C H COOH 5 0.15 pH = -log 6.5 10 log 0.25 x 4.188 0.22 = 3.97
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