NCEA Level 2 Chemistry 2025 – 400 Free Practice Questions to Pass the Exam

The classification of a weak acid refers to its ability to partially dissociate in water, resulting in a low concentration of hydrogen ions in solution. Hydrofluoric acid (HF) is indeed considered a common laboratory weak acid because it only partially ionizes when dissolved in water. This means that in an aqueous solution, only a fraction of HF molecules donate protons, creating a relatively mild acidic effect compared to strong acids, which completely dissociate.

In contrast, sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3) are examples of strong acids. These acids completely dissociate in solution, releasing hydrogen ions fully and leading to a much stronger acidic environment. The distinction between weak and strong acids is crucial in chemistry, particularly when considering reactions, pH levels, and safety in the laboratory.

Thus, since HF is commonly used in various laboratory applications and is known for its weaker dissociation, it correctly fits the definition of a common laboratory weak acid.