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Acetic acid’s pKa is 4.2 and ammonium hydroxide pKb is 3.24. What is the pH of the ammonium acetate solution?(a) 7.12(b) 7(c) 4.2(d) 7.48The question was posed to me in examination.My question is based upon Equilibrium in chapter Equilibrium of Chemistry – Class 11 |
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Answer» RIGHT answer is (d) 7.48 Easiest explanation: We know that the pH of the solution of a weak acid and a weak BASE is given by 1/2pKW + 1/2pKa – 1/2pKb. So pH = 7 + \(\FRAC{1}{2}\)[4.2 – 3.24]; pH = 7 + 0.48 = 7.48, we GET this by SUBSTITUTING acetic acid’s pKa as 4.2 and ammonium hydroxidepKb as 3.24. |
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