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Ch.16 - Acid-Base Equilibria
Chapter 16, Problem 77a

Given that Ka for acetic acid is 1.8 * 10-5 and that for hypochlorous acid is 3.0 * 10-8, which is the stronger acid?

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid Dissociation Constant (Ka)

The acid dissociation constant (Ka) quantifies the strength of an acid in solution. It is defined as the equilibrium constant for the dissociation of an acid into its conjugate base and a proton. A higher Ka value indicates a stronger acid, as it means the acid dissociates more completely in solution.
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Characteristics of Ka and Kb

Comparing Acid Strengths

To determine which acid is stronger, one can compare their Ka values directly. The acid with the larger Ka value is considered the stronger acid because it indicates a greater tendency to donate protons. In this case, comparing the Ka values of acetic acid (1.8 * 10^-5) and hypochlorous acid (3.0 * 10^-8) will reveal which acid is stronger.
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Conjugate Acid-Base Pairs

Every acid has a corresponding conjugate base formed when it donates a proton. The strength of an acid is inversely related to the strength of its conjugate base; a strong acid has a weak conjugate base. Understanding this relationship helps in predicting the behavior of acids and bases in chemical reactions and their relative strengths.
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