The K_b for methylamine (CH₃NH₂) at 25 °C is given in Appendix D. (a) Write the chemical equation for the equilibrium that corresponds to K_b.

Verified step by step guidance

1. Identify the base in the problem: Methylamine (CH_3NH_2) is a weak base.
2. Recall that the base dissociation constant, K_b, is related to the equilibrium of a base reacting with water.
3. Write the chemical equation for the reaction of methylamine with water: CH_3NH_2 + H_2O \rightleftharpoons CH_3NH_3^+ + OH^-.
4. Recognize that in this equilibrium, methylamine accepts a proton from water, forming the methylammonium ion (CH_3NH_3^+) and hydroxide ion (OH^-).
5. Ensure the equation is balanced and represents the equilibrium process for which K_b is defined.

Key Concepts

Equilibrium Constant (K_b)

The base dissociation constant, K_b, quantifies the strength of a base in solution. It is defined as the ratio of the concentration of the products to the concentration of the reactants at equilibrium for the reaction of a base with water. A higher K_b value indicates a stronger base, as it suggests a greater tendency to accept protons.

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In the context of a base like methylamine, this means that the formation of hydroxide ions and the conjugate acid reaches a stable state where their concentrations no longer change over time.

Methylamine as a Base

Methylamine (CH₃NH₂) is an organic compound that acts as a weak base in aqueous solution. When dissolved in water, it can accept a proton (H⁺) from water, leading to the formation of its conjugate acid (methylammonium ion, CH₃NH₃⁺) and hydroxide ions (OH⁻). This reaction is essential for writing the equilibrium expression for K_b.