Question

An acid with the general formula RCOOH is used to make a 0.10 M solution in water. The pH of this acid solution is measured as 3.8. Calculate the extent of dissociation of this acid in the prepared solution. (The extent of dissociation is the fraction of the acid that is dissociated into the RCOO- anion and H3O cation in the aqueous solution.)

Answer 1

Answer:

0.159 \%

Explanation:

The acid will dissociate according to the reaction shown below:-

$RCOOH + H_2O\rightleftharpoons RCOO^- + H_3O^+$

Given that, pH=3.8

The concentration of can be determined from the expression fo pH as:-

pH = - log $[H^+]$

3.8  = - log $[H^+]$

$[H^+]$ = $1.59\times 10^{-4}\ M$

The initial concentration of RCOOH was 0.10 M, then the percent dissociation was- calculated as shown below:-

$\% \ dissociation=\frac{1.59\times 10^{-4}}{0.10}\times 100=0.159\ \%$