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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About Acids, Bases and Salts
Acid and base behaviour is explained through the Bronsted-Lowry transfer of protons and the Lewis donation or acceptance of electron pairs. The topic includes pH, pOH, ionisation and water equilibrium, plus salt formation and hydrolysis, where a salt solution may become acidic, basic or neutral.
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