Question

Valeric acid, HC5H9O2 (Ka = 1.5 ✕ 10−5), is used in the manufacture of magnesium valerate, a nerve-calming agent. What is the hydronium ion concentration (in M) in a 0.737 M solution of HC5H9O2? (Assume Kw = 1.01 ✕ 10−14.)

Answer 1

Answer:

$[H^+]=0.00332M$

Explanation:

Hello,

In this case, considering the dissociation of valeric acid as:

$HC_5H_9O_2 \rightleftharpoons C_5H_9O_2 ^-+H^+$

Its corresponding law of mass action is:

$Ka=\frac{[H^+][C_5H_9O_2^-]}{[HC_5H_9O_2]}$

Now, by means of the change $x$ due to dissociation, it becomes:

$Ka=\frac{(x)(x)}{0.737-x}=1.5x10^{-5}$

Solving for $x$ we obtain:

$x=0.00332M$

Thus, since the concentration of hydronium equals $x$, the answer is:

$[H^+]=x=0.00332M$

Best regards.