The Ka for the reaction of acetic acid and water is 1.8 x 10-5.

Which of the following statements is true at pH 7?

A.) there is much more acetic acid than acetate ion

B.) there is more acetate ion than acetic acid

C.) the concentration of acetate ion is equal to that of acetic acid

D.) the pH is lower than pKa of acetic acid

Refer to your other problem just below. The HH equation will do this one too.

To determine the true statement at pH 7, we need to understand the relationship between the pH and the pKa of acetic acid, as well as the ionization of acetic acid in water.

The pKa is a measure of the acidity or basicity of a substance. It represents the pH at which the substance is half ionized and half unionized. In the case of acetic acid (CH3COOH), the pKa is given as 4.75.

At pH 7, the solution is neutral, which means the concentration of hydronium ions (H3O+) is equal to the concentration of hydroxide ions (OH-). In water, a small portion of acetic acid molecules will ionize to form acetate ions (CH3COO-) and hydronium ions.

Now, we can evaluate each statement:

A.) There is much more acetic acid than acetate ion:
Since the pH is 7, which is higher than the pKa of acetic acid (4.75), the concentration of acetate ions will be more than acetic acid. Therefore, statement A is not true.

B.) There is more acetate ion than acetic acid:
As mentioned above, the concentration of acetate ions will be greater than acetic acid at pH 7. Therefore, statement B is true.

C.) The concentration of acetate ion is equal to that of acetic acid:
Since the concentration of acetate ions is greater than acetic acid at pH 7, statement C is not true.

D.) The pH is lower than pKa of acetic acid:
The pH of 7 is indeed lower than the pKa of acetic acid, which is 4.75. Therefore, statement D is true.

Based on the analysis, the correct statement is:

B.) There is more acetate ion than acetic acid