Classify each acid as strong or weak. If the acid is weak, write an expression for the acid ionization constant (K_a). a. HF

Verified step by step guidance

1. Identify the acid: HF is hydrofluoric acid.
2. Determine if the acid is strong or weak: HF is a weak acid.
3. Explain why HF is a weak acid: HF does not completely dissociate in water, meaning it only partially ionizes.
4. Write the chemical equation for the ionization of HF: \( \text{HF} \rightleftharpoons \text{H}^+ + \text{F}^- \).
5. Write the expression for the acid ionization constant \( K_a \): \( K_a = \frac{[\text{H}^+][\text{F}^-]}{[\text{HF}]} \).

Key Concepts

Strong vs. Weak Acids

Strong acids completely dissociate in water, releasing all their protons (H+), while weak acids only partially dissociate. This distinction is crucial for understanding acid behavior in solution and predicting the extent of ionization.

Acid Ionization Constant (Ka)

The acid ionization constant (Ka) quantifies the strength of a weak acid by measuring the equilibrium concentration of its ions in solution. It is defined by the expression Ka = [H+][A-]/[HA], where [H+] is the concentration of hydrogen ions, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the undissociated acid.

Hydrofluoric Acid (HF)

HF is classified as a weak acid because it does not fully dissociate in water. Its ionization can be represented by the equilibrium reaction HF ⇌ H+ + F-, and the corresponding Ka expression can be used to calculate its ionization in solution.