To analyze the statements regarding hydrochloric acid and acetic acid, let’s look at the characteristics of a strong acid versus a weak acid:
- Hydrochloric acid (HCl) is a strong acid, meaning it fully dissociates in water to produce H₃O⁺ ions and Cl⁻ ions.
- Acetic acid (CH₃COOH) is a weak acid, meaning it only partially dissociates in water, producing H₃O⁺ ions and CH₃COO⁻ ions.
Now examine each statement:
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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 not necessarily true because it depends on the initial concentrations and degree of dissociation.
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The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.
- This statement is correct. The dissociation constant (Ka) for hydrochloric acid is so large that it can be considered "infinite" for practical purposes, while the Ka for acetic acid is approximately 1.8 × 10⁻⁵.
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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. Given the same initial concentration, hydrochloric acid will produce more H₃O⁺ ions than acetic acid because it completely dissociates.
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The pH of a solution of hydrochloric acid must be less than the pH of a solution of acetic acid.
- This statement is generally true if both acids are at the same initial concentration, as a strong acid like HCl will yield a lower pH compared to a weak acid like acetic acid.
Therefore, the correct statement is:
The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.