Acid Base Solutions Quick Check

Question

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

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

If the initial concentration of each acid is the same, then acetic acid will produce more H3O+ ions than hydrochloric 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.
The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.

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

Answer 1

To determine the correct statement about hydrochloric acid (HCl) and acetic acid (CH₃COOH), we can analyze the implications of strong vs. weak acids.

1. Hydrochloric acid is a strong acid, which means it dissociates completely in water. As a result, if HCl is present in a solution, it will produce a high concentration of H₃O⁺ (hydronium ions) and thus a lower pH.

2. Acetic acid is a weak acid, meaning it only partially dissociates in water. Therefore, even at the same initial concentration, acetic acid will produce fewer H₃O⁺ ions than HCl.

Now, let's evaluate each response:

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

   • This is generally true because HCl dissociates completely, while acetic acid does not.

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

   • This is false. HCl will produce significantly more H₃O⁺ ions because it is a strong acid and dissociates entirely.

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

   • True. HCl being a strong acid has a very large dissociation constant (it essentially completely dissociates), whereas acetic acid has a much smaller dissociation constant.

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

   • This statement is also true, as HCl generates a higher concentration of H₃O⁺, leading to a lower pH compared to that of acetic acid.

Given the options and analyses provided, the two correct statements are:

• "A solution of hydrochloric acid at equilibrium will have a greater concentration of solute than a solution of acetic acid at equilibrium."
• "The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid."
• "The pH of a solution of hydrochloric acid must be less than the pH of a solution of acetic acid."

However, if you are looking for one correct statement, it would be:

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

This is a fundamental concept that clearly differentiates the strength of the two acids.