Neco Model Questions Vol1 2018 Chemistry Question 23

Practice objective / multiple choice question 23 from the 2018 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2018 Chemistry Objective / Multiple Choice Hard Difficulty
Question 23 NECO_MODEL_QUESTIONS_VOL1 • 2018 • CHEMISTRY • objective
Neco Model Questions Vol1 2018 Chemistry Question 23 diagram

A laboratory apparatus for collecting a gas over water is shown in the diagram. A piece of magnesium (0.500 g) is placed in excess hydrochloric acid. The hydrogen gas produced is collected over water, giving a measured volume of 250 mL at 25 °C and a total pressure of 750 mmHg. The vapour pressure of water at 25 °C is 23.8 mmHg. Using the diagram, calculate (a) the number of moles of hydrogen gas actually collected and (b) the percentage yield of hydrogen based on the stoichiometric amount expected from the magnesium sample.

Answer Options

A. (a) 0.0125 mol of H₂ collected. (b) Percentage yield ≈ 60.5 % (≈61 %).
Correct Answer B. (a) 0.0098 mol of H₂ collected. (b) Percentage yield ≈ 47.6 % (≈48 %).
C. (a) 0.0083 mol of H₂ collected. (b) Percentage yield ≈ 40.2 % (≈40 %).
D. (a) 0.0102 mol of H₂ collected. (b) Percentage yield ≈ 49.5 % (≈50 %).
Correct Answer
B
Correct Option:
(a) 0.0098 mol of H₂ collected. (b) Percentage yield ≈ 47.6 % (≈48 %).

About This Question

This is Neco Model Questions Vol1 2018 Chemistry Question 23. It is one of the objective questions from the 2018 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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