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Ch. 4 - Acids and Bases: Electron Flow
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
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All textbooksMullins 1st EditionCh. 4 - Acids and Bases: Electron FlowProblem 62f(iii,iv)
Chapter 3, Problem 62f(iii,iv)

For the following acid–base pairs, (iii) predict the favored side of equilibrium; (iv) calculate ;
(f) Chemical equation illustrating an acid-base reaction with equilibrium representation.

Verified step by step guidance
1
Step 1: Identify the acid and base on both sides of the equilibrium. For each pair, determine which species donates a proton (acid) and which accepts a proton (base).
Step 2: Use the pKa values of the acids on both sides of the equilibrium. Recall that the strength of an acid is inversely related to its pKa value: a lower pKa indicates a stronger acid.
Step 3: Predict the favored side of the equilibrium. The equilibrium will favor the side with the weaker acid and weaker base. Compare the pKa values of the acids on both sides to determine this.
Step 4: Calculate the equilibrium constant (K_eq) using the relationship between the pKa values of the acids: \( \text{K}_\text{eq} = 10^{\text{pKa (acid on left)} - \text{pKa (acid on right)}} \).
Step 5: Interpret the result. If \( \text{K}_\text{eq} > 1 \), the equilibrium favors the products. If \( \text{K}_\text{eq} < 1 \), the equilibrium favors the reactants.

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Key Concepts

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

Acid-Base Theory

Acid-base theory explains the behavior of acids and bases in chemical reactions. According to the Brønsted-Lowry theory, acids are proton donors while bases are proton acceptors. Understanding this concept is crucial for predicting the direction of equilibrium in acid-base reactions, as the stronger acid will favor the formation of the weaker acid and base.
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The Lewis definition of acids and bases.

Equilibrium Constant (K)

The equilibrium constant (K) quantifies the ratio of the concentrations of products to reactants at equilibrium for a given reaction. It provides insight into the position of equilibrium; a larger K value indicates that products are favored, while a smaller K suggests that reactants are favored. Calculating K is essential for determining the favored side of an acid-base equilibrium.
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The relationship between equilibrium constant and pKa.

pKa and pKb Values

pKa and pKb values are measures of the strength of acids and bases, respectively. The pKa value indicates the acidity of a compound, with lower values signifying stronger acids, while pKb indicates basicity, with lower values signifying stronger bases. These values are critical for predicting the favored side of equilibrium, as they allow for comparison between the strengths of the acids and bases involved.
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Related Practice
Textbook Question

For the following acid–base pairs, (iii) predict the favored side of equilibrium;

(e)

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Textbook Question

For the following acid–base pairs, (v) show a mechanism for the reaction; and (vi) draw a reaction coordinate diagram.

(f)

1099
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Textbook Question

Identify the stronger base in each pair. Explain your choice. Citing pKa values is not an acceptable answer.

(a)

1161
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Textbook Question

For the following acid–base pairs, (i) complete the reaction; (ii) identify the acid (A), base (B), conjugate acid (CA), and conjugate base (CB);

(f)

1181
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Textbook Question

For the following acid–base pairs, (iii) predict the favored side of equilibrium; (iv) calculate Keq;

(h)

1266
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Textbook Question

For the following acid–base pairs,

(i) complete the reaction;

(ii) identify the acid (A), base (B), conjugate acid (CA), and conjugate base (CB);

(e)

989
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