Neco Model Questions Vol1 2020 Chemistry Question 31

Practice objective / multiple choice question 31 from the 2020 Neco Model Questions Vol1 Chemistry examination.

Neco Model Questions Vol1 2020 Chemistry Objective / Multiple Choice Hard Difficulty
Question 31 NECO_MODEL_QUESTIONS_VOL1 • 2020 • CHEMISTRY • objective

An impure copper sample weighing 10.0 g contains 85 % Cu and 15 % Zn by mass. The sample is treated with excess dilute nitric acid which dissolves Zn but not Cu. The resulting solution is then treated with aqueous ammonia to form the tetraamminecopper(II) complex, which is subsequently reduced by adding excess Zn metal to precipitate pure copper. After the entire process, 5.6 g of pure copper is recovered. (a) Calculate the overall percent recovery of copper. (b) Determine the mass of Zn that must have reacted with the copper complex during the reduction step. (c) Briefly explain why Zn dissolves in the nitric acid step while Cu does not.)

Answer Options

A. Percent recovery = 72.3 %; Zn required = 4.92 g
B. Percent recovery = 65.9 %; Zn required = 4.00 g
Correct Answer C. Percent recovery = 65.9 %; Zn required = 5.76 g
D. Percent recovery = 58.4 %; Zn required = 6.31 g
Correct Answer
C
Correct Option:
Percent recovery = 65.9 %; Zn required = 5.76 g

About This Question

This is Neco Model Questions Vol1 2020 Chemistry Question 31. It is one of the objective questions from the 2020 Neco Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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