Question
Hydrochloric acid is a strong acid. Acetic acid is a weak acid. Which statement about hydrochloric acid and acetic acid is correct?
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.
if the initial concentration of each acid is the same, then acetic acid will produce more H3O+ ions than hydrochloric acid.
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.
if the initial concentration of each acid is the same, then acetic acid will produce more H3O+ ions than hydrochloric acid.
Answers
GPT-4o mini
Let's analyze each of the statements in the context of hydrochloric acid (HCl) being a strong acid and acetic acid (CH₃COOH) being a weak acid:
1. **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. While hydrochloric acid completely dissociates in solution, leading to a higher concentration of ions, acetic acid does not fully dissociate. However, if both solutions start with the same initial concentration of acid, the total concentration of H⁺ ions (which correlates to "solute" concentration in this context) would likely be higher for HCl. Still, the word "solute" can be ambiguous here since acetic acid will have more undissociated molecules present at equilibrium.
2. **The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.**
- This statement is correct. Hydrochloric acid (HCl) is a strong acid and completely dissociates in water, while acetic acid (CH₃COOH) is a weak acid and has a much smaller dissociation constant (Ka). For strong acids like HCl, the dissociation constant is often considered to approach infinity.
3. **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 the hydrochloric acid solution and the acetic acid solution have the same initial concentration. Since HCl completely dissociates and contributes more H₃O⁺ ions than the weakly dissociating acetic acid, its pH will be lower.
4. **If the initial concentration of each acid is the same, then acetic acid will produce more H₃O⁺ ions than hydrochloric acid.**
- This statement is incorrect. HCl, being a strong acid, will produce more H₃O⁺ ions than acetic acid (a weak acid) if the initial concentrations are the same, since HCl completely dissociates while acetic acid does not.
In summary, the correct statements from your options are:
- 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.
1. **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. While hydrochloric acid completely dissociates in solution, leading to a higher concentration of ions, acetic acid does not fully dissociate. However, if both solutions start with the same initial concentration of acid, the total concentration of H⁺ ions (which correlates to "solute" concentration in this context) would likely be higher for HCl. Still, the word "solute" can be ambiguous here since acetic acid will have more undissociated molecules present at equilibrium.
2. **The dissociation constant for hydrochloric acid is greater than the dissociation constant for acetic acid.**
- This statement is correct. Hydrochloric acid (HCl) is a strong acid and completely dissociates in water, while acetic acid (CH₃COOH) is a weak acid and has a much smaller dissociation constant (Ka). For strong acids like HCl, the dissociation constant is often considered to approach infinity.
3. **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 the hydrochloric acid solution and the acetic acid solution have the same initial concentration. Since HCl completely dissociates and contributes more H₃O⁺ ions than the weakly dissociating acetic acid, its pH will be lower.
4. **If the initial concentration of each acid is the same, then acetic acid will produce more H₃O⁺ ions than hydrochloric acid.**
- This statement is incorrect. HCl, being a strong acid, will produce more H₃O⁺ ions than acetic acid (a weak acid) if the initial concentrations are the same, since HCl completely dissociates while acetic acid does not.
In summary, the correct statements from your options are:
- 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.