Question

A 0.010 M aqueous solution of a weak acid HA has a pH of 4.0. What is the degree of ionization of HA in the solution

Answer 1

`\alpha =0.0009995`

Step-by-step explanation:

Hello,

In this case, given the pH of the weak acid HA, we can obtain the concentration of hydrogen in the solution as shown below:

`pH=-log([H^+]})`

`[H^+]=10^(-pH)=10^(-4.0)=1x10^(-4)M`

In such a way, the degree of ionization (
`\alpha`) is computed as:

`Ka=(\alpha ^2C_0)/(1-\alpha)`

Whereas
`C_0` is 0.010 M and the acid dissociation constant is:

`Ka=((1x10^(-4))^2)/(1-1x10^(-4))=1x10^(-4)`

Thus, solving for
`\alpha`, we obtain:

`\alpha =0.0009995`

Regards.