Hydrochloric acid is a strong acid. Acetic acid is a weak acid. Which statement about hydrochloric acid and acetic acid is correct? (1 point)

Question

The pH of a solution of hydrochloric acid must be less than the pH of a solution of acetic acid

If the initial concentration of each acid is the same, then acetic acid will produce more H_{3} O^ + ions than hydrochloric acid.

The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.

A solution of hydrochloric acid at equilibrium will have a greater concentration of solute than a solution of acetic acid at equilibrium.

Answer 1

To assess the statements regarding hydrochloric acid (HCl) and acetic acid (CH₃COOH), let's evaluate each one:

1. "The pH of a solution of hydrochloric acid must be less than the pH of a solution of acetic acid."

   • This is generally true because HCl is a strong acid and fully dissociates in solution, producing a higher concentration of H₃O⁺ ions compared to the weak, partially dissociating acetic acid for the same initial concentration. Thus, the pH of a strong acid solution is expected to be lower than that of a weak acid solution at the same concentration.

2. "If the initial concentration of each acid is the same, then acetic acid will produce more H₃O⁺ ions than hydrochloric acid."

   • This statement is false. HCl, as a strong acid, completely dissociates in solution, producing more H₃O⁺ ions than acetic acid, which only partially dissociates.

3. "The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid."

   • This statement is true. HCl has a very high dissociation constant (it fully dissociates), while the dissociation constant (Ka) for acetic acid is much smaller, reflecting its weak acid nature.

4. "A solution of hydrochloric acid at equilibrium will have a greater concentration of solute than a solution of acetic acid at equilibrium."

   • This statement is somewhat misleading. The concentration of HCl solutions is commonly higher due to its complete dissociation, whereas the concentration of acetic acid will be lower because some will remain undissociated in equilibrium. Therefore, without specifying situations or initial concentrations, this statement could be interpreted in different ways.

Considering the evaluations, the following statements are true:

• Statement 1 is generally true.
• Statement 3 is also true.

The most universally correct and clear statement regarding the characteristics of the two acids, particularly in the context of their dissociation and strength as acids, is:

• The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.