Which statement correctly identifies hydrochloric acid?

Which statement correctly identifies hydrochloric acid?

• A. HCl is a weak acid
• B. HCl is a base
• C. HCl is a salt
• D. HCl is a strong acid

Answer: (D)

The concept being tested is how we classify acids by their behavior in water. Hydrochloric acid is a strong acid because it dissociates completely in aqueous solution to produce hydronium and chloride ions. In other words, HCl donates its proton fully: HCl + H2O → H3O+ + Cl−, so essentially every molecule contributes a proton and the solution contains mainly ions, not undissociated HCl. This complete ionization is what gives a very high degree of acidity and a very low pH for a given concentration. It’s not a base, since bases accept protons or donate electron pairs, and it’s not a salt, which is an ionic compound formed from a reaction between an acid and a base.

The concept being tested is how we classify acids by their behavior in water. Hydrochloric acid is a strong acid because it dissociates completely in aqueous solution to produce hydronium and chloride ions. In other words, HCl donates its proton fully: HCl + H2O → H3O+ + Cl−, so essentially every molecule contributes a proton and the solution contains mainly ions, not undissociated HCl. This complete ionization is what gives a very high degree of acidity and a very low pH for a given concentration. It’s not a base, since bases accept protons or donate electron pairs, and it’s not a salt, which is an ionic compound formed from a reaction between an acid and a base.