Question

What is the ratio of acetic acid (pK = 4.76) to acetate(-) in a 1.0 M acetate solution with a pH = 5.76?

a) 1:10
b) 1:1
c) 10:1
d) 1:100

Answer 1

The ratio of acetic acid to acetate(-) in a 1.0 M acetate solution with a pH = 5.76 is 1:10. Option a.

Step-by-step explanation:

The ratio of acetic acid to acetate(-) in a solution can be determined using the Henderson-Hasselbalch equation:

pH = pKa + log([A-]/[HA]),

where [A-] is the concentration of acetate(-), [HA] is the concentration of acetic acid, and pKa is the negative logarithm of the acid dissociation constant (pKa = -log(Ka)).

In this case, the pH is 5.76 and the pKa is 4.76.

Plugging in the values, we have:

5.76 = 4.76 + log([A-]/[HA]).

Simplifying, we find:

log([A-]/[HA]) = 5.76 - 4.76 = 1.

Taking the antilog, we get:

[A-]/[HA] = 10^1 = 10.

Therefore, the ratio of acetic acid to acetate(-) is 1:10. The correct answer is a) 1:10.