Write equations showing how each weak base ionizes water to form OH^–. Also write the corresponding expression for K_b. a. NH₃ b. HCO₃^– c. CH₃NH₂

Verified step by step guidance

1. Identify the weak base and its reaction with water. For each base, write the chemical equation showing the base accepting a proton from water to form its conjugate acid and hydroxide ion (OH^-).
2. For NH_3, write the equation: NH_3 + H_2O \rightleftharpoons NH_4^+ + OH^-.
3. For HCO_3^-, write the equation: HCO_3^- + H_2O \rightleftharpoons H_2CO_3 + OH^-.
4. For CH_3NH_2, write the equation: CH_3NH_2 + H_2O \rightleftharpoons CH_3NH_3^+ + OH^-.
5. Write the expression for the base dissociation constant (K_b) for each reaction. For example, for NH_3, K_b = \frac{[NH_4^+][OH^-]}{[NH_3]} and similarly for the others.

Key Concepts

Ionization of Weak Bases

Weak bases partially ionize in water, meaning they do not completely dissociate into ions. For example, ammonia (NH3) reacts with water to form ammonium (NH4+) and hydroxide ions (OH–). This process is essential for understanding how weak bases contribute to the pH of a solution and the formation of hydroxide ions.

Equilibrium Constant (Kb)

The base dissociation constant (Kb) quantifies the strength of a weak base in solution. It is defined as the ratio of the concentration of the products (the ions formed) to the concentration of the reactants (the un-ionized base) at equilibrium. A higher Kb value indicates a stronger weak base, which ionizes more in water.

Hydrolysis Reaction

Hydrolysis reactions occur when a base reacts with water to produce hydroxide ions. In the context of weak bases, this reaction is crucial for determining the pH of the solution. For example, when bicarbonate (HCO3–) acts as a weak base, it accepts a proton from water, leading to the formation of carbonate (CO3^2–) and hydroxide ions (OH–).