(a) Calculate the percent ionization of 0.0075 M butanoic acid 1Ka = 1.5 * 10-52.

Verified step by step guidance

1. Identify the given values: the concentration of butanoic acid (C4H8O2) is 0.0075 M, and the acid dissociation constant (Ka) is 1.5 * 10^-5.
2. Write the expression for the equilibrium constant (Ka) for the dissociation of butanoic acid: Ka = [C4H7O2-][H+] / [C4H8O2].
3. Assume that the concentration of H+ ions at equilibrium is x. Since butanoic acid is a weak acid, it dissociates slightly, and the concentrations of C4H7O2- and H+ will both be x, while the concentration of undissociated C4H8O2 will be (0.0075 - x).
4. Substitute the assumed concentrations into the Ka expression and solve for x, which represents the concentration of H+ ions at equilibrium.
5. Calculate the percent ionization by using the formula: Percent Ionization = (Concentration of ionized acid / Initial concentration of acid) * 100%. Substitute x for the concentration of ionized acid and 0.0075 M for the initial concentration.

Key Concepts

Ionization of Acids

Ionization refers to the process by which an acid donates protons (H+) to water, forming hydronium ions (H3O+) and its conjugate base. The extent of ionization is crucial for understanding the strength of an acid; strong acids ionize completely, while weak acids, like butanoic acid, only partially ionize in solution.

Percent Ionization

Percent ionization is a measure of the degree to which an acid dissociates in solution, expressed as a percentage. It is calculated using the formula: (concentration of ionized acid / initial concentration of acid) × 100%. This concept helps in comparing the strength of different acids and understanding their behavior in dilute solutions.

Equilibrium Constant (Ka)

The acid dissociation constant (Ka) quantifies the strength of an acid in solution. It is defined as the ratio of the concentration of the products (ionized form) to the concentration of the reactants (non-ionized form) at equilibrium. A smaller Ka value indicates a weaker acid, which is relevant for calculating percent ionization in weak acids like butanoic acid.