Question

Of the following solutions, which has the greatest buffering capacity?

a. 0.365M HC2H3O2 and 0.497 M NaC2H3O2
b. 0.521 M HC2H3O2 and 0.217 M NaC2H3O2
c. 0.821 M HC2H3O2 and 0.713 M NaC2H3O2
d. 0.121 M HC2H3O2 and 0.116 M NaC2H3O2

Answer 1

d. 0.121 M HC2H3O2 and 0.116 M NaC2H3O2

Step-by-step explanation:

Hello,

In this case, since the pH variation is analyzed via the Henderson-Hasselbach equation:

`pH=pKa+log(([Base])/([Acid]) )`

We can infer that the nearer to 1 the ratio of of the concentration of the base to the concentration of the acid the better the buffering capacity. In such a way, since the sodium acetate is acting as the base and the acetic acid as the acid, we have:

a.
`([Base])/([Acid])=(0.497M)/(0.365M)=1.36`

b.
`([Base])/([Acid])=(0.217M)/(0.521M)=0.417`

c.
`([Base])/([Acid])=(0.713M)/(0.821M)=0.868`

d.
`([Base])/([Acid])=(0.116M)/(0.121M)=0.959`

Therefore, the d. solution has the best buffering capacity.

Regards.