AQA GCSE · Chemistry 8462

Yield and atom economy of chemical reactions (chemistry only): Practice Questions

5 multiple-choice questions marked as you go, and 4 written questions with worked solutions. All on Yield and atom economy of chemical reactions (chemistry only).

9 questions21 marksFree, no account

Question 1

1 mark

What is meant by the term atom economy (atom utilisation)?

Question 2

1 mark

A student calculates that the maximum theoretical mass of calcium oxide (\(\text{CaO}\)) that could be produced from a reaction is \(50\text{g}\). After carrying out the experiment, the actual mass of calcium oxide obtained is \(35\text{g}\).
What is the percentage yield for this reaction?

Question 3

1 mark

An industrial scientist is evaluating two pathways to create Product Z.

Pathway A: Atom economy = \(95\%\), Percentage yield = \(30\%\)
Pathway B: Atom economy = \(40\%\), Percentage yield = \(90\%\)

Which statement correctly identifies a factor in choosing the most sustainable pathway?

Question 4

1 mark

Which of the following is the correct formula for calculating the percentage yield of a chemical reaction?

Question 5

1 mark

In the industrial production of hydrogen, methane reacts with steam according to the equation:
\(\text{CH}_4 + \text{H}_2\text{O} \rightarrow 3\text{H}_2 + \text{CO}\)
Calculate the percentage atom economy for the production of hydrogen (\(\text{H}_2\)) in this reaction.
(Relative atomic masses: \(\text{H} = 1\), \(\text{C} = 12\), \(\text{O} = 16\))

Question 6

2 marks

A chemical reaction has a theoretical yield of \(25.0\text{g}\). If the actual yield of the product collected is \(18.5\text{g}\), calculate the percentage yield for this reaction.

Write your answer out first, then check it against the worked solution.

Question 7

3 marks

Titanium is extracted from titanium(IV) chloride using sodium according to the equation:
\(\text{TiCl}_4 + 4\text{Na} \rightarrow \text{Ti} + 4\text{NaCl}\)
Calculate the percentage atom economy for the production of titanium (\(\text{Ti}\)).
(Relative atomic masses: \(\text{Na} = 23\), \(\text{Cl} = 35.5\), \(\text{Ti} = 48\))

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Question 8

6 marks

Ethanol is produced by the hydration of ethene:
\(\text{C}_2\text{H}_4 + \text{H}_2\text{O} \rightarrow \text{C}_2\text{H}_5\text{OH}\)
Calculate the percentage atom economy for this reaction and explain why this specific value is significant for sustainable development.

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Question 9

5 marks

Methanol (\(CH_3OH\)) can be produced by the reaction of carbon monoxide with hydrogen:
\(CO(g) + 2H_2(g) \rightarrow CH_3OH(l)\)

(a) Calculate the percentage atom economy for the production of methanol in this reaction. (2 points)

(b) In an industrial process, 500 kg of carbon monoxide reacted to produce 420 kg of methanol. Calculate the percentage yield of methanol for this process.
(Relative atomic masses: \(H = 1, C = 12, O = 16\)) (3 points)

Write your answer out first, then check it against the worked solution.

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