Give the conjugate base of the following Brønsted–Lowry acids: (i) HCOOH, (ii) HPO42-.

Verified step by step guidance

1. Identify the Brønsted–Lowry acid in each case. A Brønsted–Lowry acid is a substance that can donate a proton (H⁺).
2. For each acid, remove one proton (H⁺) to find the conjugate base. This involves subtracting an H⁺ from the chemical formula of the acid.
3. For (i) HCOOH, remove an H⁺ to form the conjugate base. The resulting formula will be HCOO⁻.
4. For (ii) HPO₄²⁻, remove an H⁺ to form the conjugate base. The resulting formula will be PO₄³⁻.
5. Verify that the charge of the conjugate base is one unit more negative than the original acid, as losing a proton (H⁺) decreases the charge by one.

Key Concepts

Brønsted–Lowry Acid-Base Theory

The Brønsted–Lowry theory defines acids as proton donors and bases as proton acceptors. This framework emphasizes the transfer of protons (H+) in chemical reactions, allowing for a broader understanding of acid-base behavior beyond just the presence of hydroxide ions. In this context, identifying conjugate bases involves recognizing the species formed when an acid donates a proton.

Conjugate Acid-Base Pairs

Conjugate acid-base pairs consist of two species that differ by the presence of a single proton. When an acid donates a proton, it transforms into its conjugate base, while the base that accepts the proton becomes its conjugate acid. Understanding these pairs is crucial for predicting the outcome of acid-base reactions and determining the strength of acids and bases.

Dissociation of Acids

The dissociation of acids refers to the process by which an acid releases protons into solution. For example, when formic acid (HCOOH) dissociates, it loses a proton to form its conjugate base, formate (HCOO-). Similarly, the dissociation of hydrogen phosphate (HPO4^2-) results in the formation of its conjugate base, phosphate (PO4^3-). This concept is essential for identifying conjugate bases in acid-base reactions.