The fluoride ion is the conjugate base of the weak acid hydrofluoric acid. The value of Kb for F-, is 1.39×10-11. Write the equation for the reaction that goes with this equilibrium constant.

F⁻(aq) + H₂O(l) ⇄ HF(aq) + OH⁻(aq)

Explanation:

According to Brönsted-Lowry acid-base theory, an acid is a substance that donates H⁺ ions. In this sense, hydrofluoric acid is an acid according to the following equation.

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq)

According to Brönsted-Lowry acid-base theory, a base is a substance that accepts H⁺ ions. In this sense, the fluoride ion is a base according to the following equation.

F⁻(aq) + H₂O(l) ⇄ HF(aq) + OH⁻(aq)

The equilibrium constant for this reaction is Kb = 1.39 × 10⁻¹¹.