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InterviewSolution
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What should be the ratio of concentrations of formate ion and formic acid in a buffer solution so that its pH should be 4? Around what pH will this buffer have maximum buffer capacity?Ka = 1.8 x 10-4? |
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Answer» pH = pKa + log\(\frac{[Salt]}{[Acid]}\) 4 = − log(1.8 x 10-4) + log\(\frac{[Formate]}{[Formic\,Acid]}\) 4 = 3∙74 + log\(\frac{[Formate]}{[Formic\,Acid]}\) log\(\frac{[Formate]}{[Formic\,Acid]}\) = 4- 3.47 = 0.26 \(\frac{[Formate]}{[Formic\,Acid]}\) = 1.8 The buffer capacity of this solution would be maximum near the pKa of the acid. \(\therefore\) For maximum buffer capacity pH = pKa = − log Ka = − log (1∙8 × 10−4) = 3∙74. |
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