What is the pH of 1 M solution of acetic acid ? To what volume one litre of this solution be diluted so that pH of the resulting solution will be twice of the original value ? (K_(a)=1.8xx10^(-5))

What is the pH of 1 M solution of acetic acid ? To what volume one lit

1.	What is the pH of 1 M solution of acetic acid ? To what volume one litre of this solution be diluted so that pH of the resulting solution will be twice of the original value ? (K_(a)=1.8xx10^(-5))
Answer» SOLUTION :`CH_(3)COOH rarr CH_(3)COO^(-) + H^(+)` When CONCENTRATION of `CH_(3)COOH` is 1.0 M, `'ALPHA'` is negligible. `[H^(+)] = sqrt(K_(a)C) = 4.24 xx 10^(-3)M` `pH = -log(424 xx 10^(-3))M = 2.37` Now, let us assume that solution is diluted to a volume where concentration of `CH_(3)COOH` (without considering ionisation) is x `CH_(3)COOH underset("x(1-alpha)") rarr CH_(3)COO^(-)underset("xalpha") + H^(+)underset("xalpha")` `K_(a) = xalpha^(2)/1-alpha` Also, desired pH = 2 xx 2.37 = 4.74 `[H^(+)] = 1.8 xx 10^(-5) = xalpha` `K_(a) = 1.8 xx 10^(-5) =1.8 xx 10^(-5)alpha/1-alpha` `alpha = 0.5 and x = 3.6 xx 10^(-5)M` Volume(final) `= 1//3.6 xx 10^(-5) = 27.78 xx 10^(3)L`