Consider the following reaction:
HBr + ^-C≡N ⇌ Br⁻ + HC≡N
c. What is the conjugate base of the acid on the left?
d. What is the conjugate acid of the base on the left?

Verified step by step guidance

1. Step 1: Identify the acid and base on the left side of the reaction. The acid is HBr, and the base is -C≡N (cyanide ion).
2. Step 2: Recall the definition of a conjugate base. The conjugate base is formed when an acid donates a proton (H⁺). In this case, HBr donates a proton to form Br⁻.
3. Step 3: Conclude that the conjugate base of HBr (the acid on the left) is Br⁻.
4. Step 4: Recall the definition of a conjugate acid. The conjugate acid is formed when a base accepts a proton (H⁺). In this case, -C≡N accepts a proton to form HC≡N.
5. Step 5: Conclude that the conjugate acid of -C≡N (the base on the left) is HC≡N.

Key Concepts

Conjugate Acid-Base Pairs

In acid-base chemistry, a conjugate acid is formed when a base gains a proton (H+), while a conjugate base is formed when an acid loses a proton. This relationship is crucial for understanding the dynamics of acid-base reactions, as it helps identify how substances interact in equilibrium. For example, in the reaction provided, HBr acts as an acid, and its conjugate base is Br−.

Equilibrium in Acid-Base Reactions

Acid-base reactions often reach a state of equilibrium, where the forward and reverse reactions occur at the same rate. This means that the concentrations of reactants and products remain constant over time. Understanding this concept is essential for determining the direction of the reaction and the strength of the acids and bases involved, as seen in the reaction between HBr and cyanide.

Strength of Acids and Bases

The strength of an acid or base is determined by its ability to donate or accept protons. Strong acids completely dissociate in solution, while weak acids only partially dissociate. This concept is important for predicting the behavior of substances in reactions, such as identifying the conjugate acid and base in the given equilibrium, where HBr is a strong acid and CN− is a weak base.