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Yield and atom economy
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Chemists want as much product as possible with as little waste as possible. Yield and atom economy measure this. Separate Chemistry only.
Percentage yield
percentage yield = actual yieldtheoretical yield × 100
Yields are below 100% because the reaction may be reversible, some product is lost when separating, or there are side reactions.
Yields are below 100% because the reaction may be reversible, some product is lost when separating, or there are side reactions.
Atom economy
atom economy = M_r of desired producttotal M_r of all reactants × 100
A high atom economy means less waste, which is better for the environment and cheaper.
A high atom economy means less waste, which is better for the environment and cheaper.
Choosing a route
Industry compares atom economy, yield, rate, equilibrium position, and the usefulness of by-products.
Theoretical yield is 20 g; actual yield is 15 g. Find the percentage yield.
- 1520 × 100
Answer: 75%
Percentage yield = actual ÷ theoretical × 100. Atom economy = M_r of wanted product ÷ total M_r of reactants × 100. Higher atom economy means less waste.
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