Open Question
Find the percent ionization of a 0.337 m HF solution. the ka for hf is 3.5 × 10-4. What would you expect the percent ionization to be for the same concentration of hydrochloric acid (HCl)? Explain.
17. Acid and Base Equilibrium
pH of Weak Acids
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A 0.10 M HClO(aq) solution is prepared. Calculate the pH of this solution given that the Ka of HClO is 1.58 x 10^-4.
A
pH = 2.00
B
pH = 4.00
C
pH = 5.00
D
pH = 4.83
Verified step by step guidance1
Identify the chemical equilibrium involved: HClO(aq) ⇌ H⁺(aq) + ClO⁻(aq). The dissociation of hypochlorous acid (HClO) in water is a weak acid equilibrium.
Write the expression for the acid dissociation constant (Ka): Ka = [H⁺][ClO⁻] / [HClO]. Given that Ka = 1.58 x 10^-4, this expression will help us find the concentration of H⁺ ions.
Assume that the initial concentration of HClO is 0.10 M and that the change in concentration due to dissociation is x. Therefore, at equilibrium, [H⁺] = x, [ClO⁻] = x, and [HClO] = 0.10 - x.
Substitute these equilibrium concentrations into the Ka expression: 1.58 x 10^-4 = (x)(x) / (0.10 - x). Since HClO is a weak acid, we can assume x is small compared to 0.10, simplifying the expression to 1.58 x 10^-4 ≈ x² / 0.10.
Solve for x, which represents [H⁺], and then calculate the pH using the formula pH = -log[H⁺]. This will give you the pH of the solution.
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