Compared to HCl, the acid CH3COOH is what?

Compared to HCl, the acid CH3COOH is what?

• A. HCl is weaker than CH3COOH
• B. HCl and CH3COOH are equally strong
• C. CH3COOH is weaker than HCl
• D. CH3COOH is stronger than HCl

Answer: (C)

Acid strength in water is determined by how completely the acid dissociates. Hydrochloric acid is a strong acid, so it almost completely breaks apart in solution to give H+ and Cl-. Acetic acid, on the other hand, is a weak acid; it only partially dissociates, so at the same concentration it produces far fewer H+. Since the level of H+ in solution dictates acidity, HCl is stronger and CH3COOH is weaker. This is reflected in their Ka values as well—acetic acid has a relatively small Ka, while a strong acid like HCl effectively has a much larger tendency to donate a proton in water.

Acid strength in water is determined by how completely the acid dissociates. Hydrochloric acid is a strong acid, so it almost completely breaks apart in solution to give H+ and Cl-. Acetic acid, on the other hand, is a weak acid; it only partially dissociates, so at the same concentration it produces far fewer H+. Since the level of H+ in solution dictates acidity, HCl is stronger and CH3COOH is weaker. This is reflected in their Ka values as well—acetic acid has a relatively small Ka, while a strong acid like HCl effectively has a much larger tendency to donate a proton in water.