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?

Verified step by step guidance

1. insert step 1> Determine the definition of acid strength in terms of the acid dissociation constant (K_a). A stronger acid has a larger K_a value, indicating a greater degree of ionization in solution.
2. insert step 2> Compare the given K_a values for acetic acid and hypochlorous acid. Acetic acid has a K_a of 1.8 \times 10^{-5}, while hypochlorous acid has a K_a of 3.0 \times 10^{-8}.
3. insert step 3> Analyze the magnitude of the K_a values. Since 1.8 \times 10^{-5} is greater than 3.0 \times 10^{-8}, acetic acid has a larger K_a value.
4. insert step 4> Conclude that acetic acid is the stronger acid because it has a larger K_a value, indicating it ionizes more in solution compared to hypochlorous acid.
5. insert step 5> Remember that the strength of an acid is directly related to its ability to donate protons, which is reflected in the magnitude of its K_a value.

Key Concepts

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.

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.

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.