Gce Model Questions Vol1 2017 Chemistry Question 49

Practice objective / multiple choice question 49 from the 2017 Gce Model Questions Vol1 Chemistry examination.

Gce Model Questions Vol1 2017 Chemistry Objective / Multiple Choice Hard Difficulty
Question 49 GCE_MODEL_QUESTIONS_VOL1 • 2017 • CHEMISTRY • objective

A 5.00 g sample of benzoic acid (C₆H₅COOH, M = 122.12 g·mol⁻¹) is reacted with excess ethanol in the presence of concentrated H₂SO₄ to form ethyl benzoate. The ester is then isolated and purified, giving 4.20 g of product.\n(a) Write the balanced equation for the esterification.\n(b) Calculate the percentage yield of ethyl benzoate.\n(c) The IR spectrum of the product shows a strong absorption at 1735 cm⁻¹ and no absorption near 1700 cm⁻¹. Explain what this indicates about the functional group present.

Answer Options

A. a) C₆H₅COOH + CH₃CH₂OH ⇌ C₆H₅COOCH₂CH₃ + H₂O; b) 75.0 %; c) The 1735 cm⁻¹ band indicates a carbonyl, but the presence of a ~1700 cm⁻¹ band would suggest a carboxylic‑acid remains.
B. a) C₆H₅COOH + CH₃CH₂OH ⇌ C₆H₅COOHCH₃ + H₂O; b) 68.3 %; c) The 1735 cm⁻¹ band is characteristic of an aldehyde C=O, and the lack of ~1700 cm⁻¹ band confirms no acid.
C. a) C₆H₅COOH + CH₃CH₂OH ⇌ C₆H₅COOCH₂CH₃ + H₂; b) 58.2 %; c) The 1735 cm⁻¹ band shows an ester C=O, and the missing ~1700 cm⁻¹ band indicates the acid has been reduced.
Correct Answer D. a) C₆H₅COOH + CH₃CH₂OH ⇌ C₆H₅COOCH₂CH₃ + H₂O; b) 68.3 %; c) The 1735 cm⁻¹ band confirms an ester C=O, and the missing ~1700 cm⁻¹ band shows the carboxylic‑acid group is absent.
Correct Answer
D
Correct Option:
a) C₆H₅COOH + CH₃CH₂OH ⇌ C₆H₅COOCH₂CH₃ + H₂O; b) 68.3 %; c) The 1735 cm⁻¹ band confirms an ester C=O, and the missing ~1700 cm⁻¹ band shows the carboxylic‑acid group is absent.

About This Question

This is Gce Model Questions Vol1 2017 Chemistry Question 49. It is one of the objective questions from the 2017 Gce Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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