Write an equation for the acid-base equilibrium of:
a.Pyrrolidine and water
Label each species in the equilibrium as either an acid or a base.

Verified step by step guidance

1. Identify the chemical nature of pyrrolidine. Pyrrolidine is a cyclic amine, which means it acts as a weak base because it has a lone pair of electrons on the nitrogen atom that can accept a proton (H⁺).
2. Write the general reaction for a base reacting with water. A base reacts with water by accepting a proton from water, forming its conjugate acid and hydroxide ions (OH⁻).
3. Set up the equilibrium equation for pyrrolidine and water. Pyrrolidine (C₄H₉NH) reacts with water (H₂O) to form its conjugate acid (C₄H₉NH₂⁺) and hydroxide ions (OH⁻). The equation is: $C₄H₉NH\; +\; H₂O\; \rightleftharpoons \; C₄H₉NH₂⁺\; +\; OH⁻$
4. Label each species in the equilibrium. Pyrrolidine (C₄H₉NH) is the base because it accepts a proton. Water (H₂O) acts as the acid because it donates a proton. The conjugate acid is C₄H₉NH₂⁺, and the conjugate base is OH⁻.
5. Verify the reaction follows the Brønsted-Lowry acid-base theory. In this theory, acids are proton donors, and bases are proton acceptors. Pyrrolidine accepts a proton, and water donates a proton, confirming the reaction aligns with this theory.

Key Concepts

Acid-Base Theory

Acid-base theory explains the behavior of acids and bases in chemical reactions. According to the Brønsted-Lowry theory, an acid is a proton donor, while a base is a proton acceptor. This framework helps in understanding how substances interact in equilibrium, particularly in aqueous solutions.

Equilibrium Constant

The equilibrium constant (K) quantifies the ratio of concentrations of products to reactants at equilibrium for a given reaction. In acid-base equilibria, it helps determine the strength of acids and bases. A larger K value indicates a stronger acid or base, as it favors the formation of products.

Pyrrolidine as a Base

Pyrrolidine is a cyclic amine that acts as a weak base due to the presence of a lone pair of electrons on the nitrogen atom. In the context of acid-base equilibrium with water, pyrrolidine can accept a proton from water, forming its conjugate acid and hydroxide ions. Understanding its role is crucial for labeling species in the equilibrium.