The ionization constant of HF is 7.2 × 10−4. What is the molar concentration of H+ in a solution which is 0.353 molar in HF and 0.145 molar in KF?
Use the HH equation.
To find the molar concentration of H+ in the given solution, we need to determine the extent of ionization of HF.
The ionization constant (Ka) of HF is defined as the ratio of the concentrations of the products (H+ and F-) to the concentration of the reactant (HF) in the equilibrium expression. In this case, HF dissociates into H+ and F- ions, so the equilibrium expression can be written as:
Ka = [H+][F-] / [HF]
The problem states that the ionization constant of HF is 7.2 × 10^-4, so we can substitute this value into the equation:
7.2 × 10^-4 = [H+][F-] / [HF]
Now, let's represent the concentration of HF as [HF], the concentration of H+ as [H+], and the concentration of F- as [F-]. We know that the concentration of F- is equal to the concentration of KF, which is given as 0.145 M. The concentration of HF is given as 0.353 M. Therefore, the equation becomes:
7.2 × 10^-4 = [H+](0.145) / (0.353)
To find the concentration of H+, we can rearrange the equation:
[H+] = (7.2 × 10^-4)(0.353) / 0.145
[H+] = 1.754 × 10^-3 M
Therefore, the molar concentration of H+ in the solution is 1.754 × 10^-3 M.
To find the molar concentration of H+ in the given solution, we need to consider the ionization of HF.
HF ionizes as follows:
HF ⇌ H+ + F-
The ionization constant (Ka) of HF is given as 7.2 × 10^-4. This can be expressed as the ratio of the concentration of the products (H+ and F-) to the concentration of the reactant (HF).
Ka = [H+][F-] / [HF]
Given that the concentration of HF in the solution is 0.353 M, we can assume that the concentration of F- is also 0.353 M since HF and KF completely dissociate in solution to form H+ and F-.
Let's assume the concentration of H+ in the solution is x M.
Using the balanced equation, we can set up the following equation based on the ionization constant:
7.2 × 10^-4 = x * 0.353 / 0.353
Simplifying this equation, we find:
7.2 × 10^-4 = x
Therefore, the molar concentration of H+ in the given solution is 7.2 × 10^-4 M.