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Given a solution of acetic acid. How many times of the acid concentration, acetate salt should be added to obtain a solution with pH = 7.0 [`K_(a)` for dissociation of `CH_(3)CO OH=1.8xx10^(-5)]` |
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Answer» Suppose the concentration of the acetate salt added is x times the concentration of acetic acid solution to obtain `pH=7. "Then " [CH_(3)CO O^(-)]=x xx [CH_(3)CO OH] :. ([CH_(3)CO O^(-)])/([CH_(3)CO OH])=x` Now, for acid buffer, `pH = pK_(a) + log .(["Salt"])/("Acid"])` `:. 7 = - log (1.8xx10^(-5))+ log x or 7 = 4.76+ log x or log x = 2.24 or x = 1.73 xx 10^(2) = 173` times |
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