Question

Difficulty: HardAlkanoic Acids, Esterification, Saponification, Fats, and Oils

During the esterification reaction between ethanoic acid (CH3COOH\text{CH}_3\text{COOH}) and ethanol (C2H5OH\text{C}_2\text{H}_5\text{OH}), concentrated tetraoxosulfate(VI) acid (H2SO4\text{H}_2\text{SO}_4) is added to the reaction mixture. Which of the following statements correctly accounts for the dual function of concentrated H2SO4\text{H}_2\text{SO}_4 in maximizing the equilibrium yield of ethyl ethanoate?

  1. It functions as a catalyst to increase the reaction rate and as a dehydrating agent to absorb water, shifting the equilibrium position to the right.Answer
  2. B
    It acts as a strong inorganic acid reactant that undergoes irreversible ionic neutralization with ethanol to produce ethyl ethanoate complete to completion.
  3. C
    It serves solely as a catalyst, which selectively increases the rate of the forward reaction and permanently increases the equilibrium constant (KcK_c).
  4. D
    It acts primarily as an oxidizing agent that converts ethanol into ethanoic acid before esterification begins.

Answer

Concentrated tetraoxosulfate(VI) acid acts as both a catalyst to speed up the reaction rate and a dehydrating agent to remove water, shifting the reversible equilibrium toward the formation of ethyl ethanoate.
The correct response accurately identifies both functions of concentrated tetraoxosulfate(VI) acid in esterification: it acts as a catalyst to increase the rate at which equilibrium is reached and as a strong dehydrating agent that removes water from the system, driving the reversible equilibrium to the right to maximize ester production according to Le Chatelier's principle.

Step-by-Step Solution

1
Analyze the chemical equation for esterification
CH3COOH(l)+C2H5OH(l)CH3COOC2H5(l)+H2O(l)\text{CH}_3\text{COOH}(l) + \text{C}_2\text{H}_5\text{OH}(l) \rightleftharpoons \text{CH}_3\text{COOC}_2\text{H}_5(l) + \text{H}_2\text{O}(l)
Esterification is a reversible organic reaction between an alkanoic acid and an alkanol to form an ester and water.
2
Identify the catalytic role of concentrated H2SO4\text{H}_2\text{SO}_4
Provides H+\text{H}^+ ions to protonate the carbonyl oxygen, accelerating both forward and backward rates.
Lowering activation energy allows the system to reach equilibrium faster.
3
Identify the dehydrating role and apply Le Chatelier's principle
Concentrated H2SO4\text{H}_2\text{SO}_4 absorbs water (H2O\text{H}_2\text{O}), decreasing product concentration.
Removing a product from a reversible system shifts the equilibrium position to the right, increasing the yield of the ester.

Key Concept

Reversibility of Esterification and Dual Role of Concentrated H2SO4
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