Atom economy and greener reactions

Question 1

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. The useful product is ethanol (Mr 46). Relative masses of reactants: C₆H₁₂O₆ = 180. What is the atom economy? Give 1 decimal place.

Answer %

Question 2

Atom economy: which statement is NOT true?

• A. Selling or using by-products makes a process less wasteful.
• B. Reactions with only one product have 100 % atom economy.
• C. Green chemistry aims to use reactions with high atom economy.
• D. Atom economy is the same as percentage yield.

Question 3

Atom economy and percentage yield are different. Which statement is correct?

• A. They are always equal
• B. Atom economy is measured with a balance
• C. Yield comes from the equation only
• D. Atom economy comes from the equation; yield comes from what you actually collect

Question 4

Fe₂O₃ + 3CO → 2Fe + 3CO₂. The useful product is iron (Ar 56). Relative masses of reactants: Fe₂O₃ = 160, CO = 28. What is the atom economy? Give 1 decimal place.

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Question 5

Atom economy: which statement is NOT true?

• A. Selling or using by-products makes a process less wasteful.
• B. Green chemistry aims to use reactions with high atom economy.
• C. Thermal decomposition of calcium carbonate has 100 % atom economy for calcium oxide.
• D. Atom economy is calculated from the balanced equation.

Question 6

What does a 100 % atom economy mean?

• A. The yield is always 100 %
• B. No energy is needed
• C. The reaction is very fast
• D. All the atoms in the reactants end up in the desired product

Question 7

CaCO₃ → CaO + CO₂. The useful product is calcium oxide (Mr 56). Relative masses of reactants: CaCO₃ = 100. What is the atom economy? Give 1 decimal place.

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Question 8

Atom economy: which statement is NOT true?

• A. Green chemistry aims to use reactions with high atom economy.
• B. Atom economy is calculated from the balanced equation.
• C. Selling or using by-products makes a process less wasteful.
• D. Thermal decomposition of calcium carbonate has 100 % atom economy for calcium oxide.

Question 9

Why does a low atom economy matter for sustainability?

• A. It makes products cheaper
• B. It increases the yield
• C. It removes pollution
• D. More resources are turned into waste products

Question 10

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. The useful product is ethanol (Mr 46). Relative masses of reactants: C₆H₁₂O₆ = 180. What is the atom economy? Give 1 decimal place.

Answer %

Question 11

Atom economy: which statement is NOT true?

• A. Atom economy is calculated from the balanced equation.
• B. Reactions with only one product have 100 % atom economy.
• C. Green chemistry aims to use reactions with high atom economy.
• D. Atom economy is the same as percentage yield.

Question 12

Ethanol can be made by fermentation (atom economy 51 %) or by reacting ethene with steam (100 %). Why might a company still choose fermentation?

• A. It has a higher atom economy
• B. It uses renewable sugar crops instead of crude oil
• C. It is faster
• D. It produces purer ethanol

Question 13

Fe₂O₃ + 3CO → 2Fe + 3CO₂. The useful product is iron (Ar 56). Relative masses of reactants: Fe₂O₃ = 160, CO = 28. What is the atom economy? Give 1 decimal place.

Answer %

Question 14

Atom economy: which statement is NOT true?

• A. Selling or using by-products makes a process less wasteful.
• B. Atom economy is calculated from the balanced equation.
• C. A low atom economy means the reaction is fast.
• D. Reactions with only one product have 100 % atom economy.

Question 15

Why does a low atom economy matter for sustainability?

• A. It increases the yield
• B. More resources are turned into waste products
• C. It removes pollution
• D. It makes products cheaper

Question 16

CaCO₃ → CaO + CO₂. The useful product is calcium oxide (Mr 56). Relative masses of reactants: CaCO₃ = 100. What is the atom economy? Give 1 decimal place.

Answer %