Using qualitative reasoning for the acid–base reactions shown,
(i) which is stronger, the acid or the conjugate acid?
(ii) Which side of the reaction is favored?
(iii) Would you expect a K_eq greater than, equal to, or less than 1?
(a)

Verified step by step guidance

Step 1: Identify the acid and the conjugate acid in the reaction. The acid is the species donating a proton (H⁺), and the conjugate acid is the species formed when the base accepts a proton.

Step 2: Compare the relative strengths of the acid and the conjugate acid using pKa values. Recall that a lower pKa value indicates a stronger acid. Use qualitative reasoning to determine which is stronger.

Step 3: Determine which side of the reaction is favored. Acid-base reactions favor the side with the weaker acid and weaker base. Use the relative strengths of the acid and conjugate acid to predict the favored side.

Step 4: Analyze the equilibrium constant (K_eq) qualitatively. If the reaction favors the products, K_eq > 1. If it favors the reactants, K_eq < 1. If both sides are equally favored, K_eq ≈ 1.

Step 5: Conclude whether K_eq is greater than, equal to, or less than 1 based on the favored side of the reaction and the relative acid strengths.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Strength

Acid-base strength is determined by the ability of an acid to donate protons (H+) and the ability of a base to accept protons. Strong acids completely dissociate in solution, while weak acids only partially dissociate. The strength of an acid is often compared to its conjugate base, where a stronger acid has a weaker conjugate base, and vice versa.

Equilibrium and Reaction Favorability

In acid-base reactions, the position of equilibrium indicates which side of the reaction is favored. The side with the weaker acid and weaker base is favored, as this corresponds to a lower energy state. The equilibrium constant (K) can be used to quantify this favorability, with values greater than 1 indicating a preference for products.

Quantitative Analysis of K

The equilibrium constant (K) for an acid-base reaction provides insight into the relative strengths of the acids and bases involved. If K is greater than 1, the products are favored, indicating that the reaction proceeds to the right. Conversely, if K is less than 1, the reactants are favored, suggesting that the reaction does not proceed significantly toward products.

Recommended video:

Guided course