Neco Model Questions Vol1 2018 Chemistry Question 22

Practice objective / multiple choice question 22 from the 2018 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2018 Chemistry Objective / Multiple Choice Hard Difficulty
Question 22 NECO_MODEL_QUESTIONS_VOL1 • 2018 • CHEMISTRY • objective

Ethyl acetate is prepared by the esterification of acetic acid with ethanol: \(\mathrm{CH_3COOH + C_2H_5OH \rightleftharpoons CH_3COOC_2H_5 + H_2O}\). At 25 °C the equilibrium constant \(K_c\) is 4.0. Initially, 0.10 mol of acetic acid and 0.15 mol of ethanol are placed in a 1.00 L flask; no products are present.\n(a) Calculate the equilibrium concentrations of all species and the percentage yield of ethyl acetate based on the initial amount of acetic acid.\n(b) If the equilibrium mixture is then diluted to a total volume of 2.00 L (no additional reagents added), determine the new equilibrium concentration of ethyl acetate and the percentage yield (based on the original 0.10 mol of acetic acid).

Answer Options

A. At 1 L: [EA]=0.0900 M, [HA]=0.0100 M, [EtOH]=0.0600 M, [H₂O]=0.0900 M; % yield = 90.0 %. After dilution to 2 L the equilibrium [EA]≈0.0450 M (0.0900 mol) and the % yield based on the original 0.10 mol remains 90.0 %.
B. At 1 L: [EA]=0.0600 M, [HA]=0.0400 M, [EtOH]=0.0900 M, [H₂O]=0.0600 M; % yield = 60.0 %. After dilution to 2 L the equilibrium [EA]≈0.0300 M (0.0600 mol) and the % yield remains 60.0 %.
Correct Answer C. At 1 L: [EA]=0.0785 M, [HA]=0.0215 M, [EtOH]=0.0715 M, [H₂O]=0.0785 M; % yield = 78.5 %. After dilution to 2 L the equilibrium [EA]≈0.0393 M (0.0785 mol) and the % yield based on the original 0.10 mol remains 78.5 %.
D. At 1 L: [EA]=0.0785 M, [HA]=0.0215 M, [EtOH]=0.0715 M, [H₂O]=0.0785 M; % yield = 78.5 %. After dilution to 2 L the equilibrium [EA]≈0.0785 M (0.157 mol) and the % yield increases to 157 %.
Correct Answer
C
Correct Option:
At 1 L: [EA]=0.0785 M, [HA]=0.0215 M, [EtOH]=0.0715 M, [H₂O]=0.0785 M; % yield = 78.5 %. After dilution to 2 L the equilibrium [EA]≈0.0393 M (0.0785 mol) and the % yield based on the original 0.10 mol remains 78.5 %.

About This Question

This is Neco Model Questions Vol1 2018 Chemistry Question 22. It is one of the objective questions from the 2018 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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