Give the conjugate acid of the following Brønsted–Lowry bases: (i) SO42-, (ii) CH3NH2.

Key Concepts

Brønsted–Lowry Theory

The Brønsted–Lowry theory defines acids as proton donors and bases as proton acceptors. This framework allows us to understand acid-base reactions in terms of the transfer of protons (H+ ions). In this context, identifying the conjugate acid of a base involves determining what species is formed when the base accepts a proton.

Conjugate Acid-Base Pairs

Conjugate acid-base pairs consist of two species that differ by the presence of a proton. When a base gains a proton, it becomes its conjugate acid, while the acid that donates the proton becomes its conjugate base. Understanding these pairs is essential for predicting the outcome of acid-base reactions and for identifying the conjugate acids of given bases.

Examples of Conjugate Acids

To find the conjugate acids of specific bases, one must consider the chemical structure of the base. For instance, when the sulfate ion (SO4^2-) accepts a proton, it becomes hydrogen sulfate (HSO4^-). Similarly, when methylamine (CH3NH2) accepts a proton, it forms methylammonium (CH3NH3+). Recognizing these transformations is key to solving the problem.