Why is hydrochloric acid considered stronger than acetic acid at the same concentration?

Why is hydrochloric acid considered stronger than acetic acid at the same concentration?

• A. It has more hydrogen ions in solution
• B. It has more hydroxide ions in solution
• C. It has fewer hydrogen ions in solution
• D. It has fewer hydroxide ions in solution

Answer: (A)

When comparing acids in water, strength means how completely the acid donates protons. Hydrochloric acid is a strong acid and acetic acid is a weak acid, so at the same formal concentration, HCl dissociates essentially completely into H+ and Cl-. That leaves a higher concentration of hydrogen ions in the solution, making it more acidic. The statement that it has more hydrogen ions in solution best captures why it is considered stronger. The other ideas don’t fit because acids don’t increase hydroxide ions; stronger acids have more H+ and thus fewer OH− relative to the amount in pure water, not more. Saying fewer hydrogen ions or fewer hydroxide ions would imply weaker acidity.

When comparing acids in water, strength means how completely the acid donates protons. Hydrochloric acid is a strong acid and acetic acid is a weak acid, so at the same formal concentration, HCl dissociates essentially completely into H+ and Cl-. That leaves a higher concentration of hydrogen ions in the solution, making it more acidic. The statement that it has more hydrogen ions in solution best captures why it is considered stronger.

The other ideas don’t fit because acids don’t increase hydroxide ions; stronger acids have more H+ and thus fewer OH− relative to the amount in pure water, not more. Saying fewer hydrogen ions or fewer hydroxide ions would imply weaker acidity.