Sodium benzoate and benzoic acid of equimolar mixed to form buffer if pKa is 2 what will be pH?

Correct answer: B. 2

  • A. 1
  • B. 2
  • C. 0
  • D. None of these

Explanation

The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]). In this question, sodium benzoate acts as the conjugate base ([A-]) and benzoic acid is the weak acid ([HA]). Since they are mixed in equimolar amounts, [A-] = [HA], thus the log term becomes zero. Therefore, the pH equals the pKa, which is 2. Option B is correct. Option A and C are incorrect as they do not match the pKa value, and Option D is incorrect because there is indeed a correct answer.

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