Question

The ionization constant (Ka) of HF is 6.7 × 10⁻⁴. Which of the following is true in a 0.1 M solution of this acid?

a. [H⁺] = 6.7 × 10⁻⁴ M
b. [H⁺] = 0.1 M
c. [HF] = 6.7 × 10⁻⁴ M
d. [H⁺] = [F⁻]

Answer 1

In a 0.1 M solution of HF, the concentration of hydronium ions is 0.008 M. The correct option is d. [H⁺] = [F⁻].

Step-by-step explanation:

The ionization constant (Ka) of HF is 6.7 × 10⁻⁴. In a 0.1 M solution of this acid, the concentration of hydronium ions ([H⁺]) can be determined using the equation: [H⁺] = √(Ka x [HF])

Substituting the values, [H⁺] = √(6.7 × 10⁻⁴ x 0.1) = 0.008 M. Therefore, option a. [H⁺] = 6.7 × 10⁻⁴ M is not true. Option b. [H⁺] = 0.1 M is also not true. Option c. [HF] = 6.7 × 10⁻⁴ M is also not true.

The correct option is d. [H⁺] = [F⁻], meaning the concentration of hydronium ions is equal to the concentration of fluoride ions in the solution.