Percentage Yield Flashcards

All 6 cards in this deck

What is meant by the yield of a reaction?

The amount (mass) of product obtained from the reaction.

What is the formula for percentage yield?

$\%\text{ yield} = \frac{\text{mass of product actually made}}{\text{maximum theoretical mass of product}} \times 100$

Give three reasons why the actual yield of a reaction is less than the theoretical yield.

1. The reaction is reversible, so it does not go to completion.
2. Some product is lost when it is separated from the reaction mixture.
3. Some reactants react in unexpected ways (side reactions).

True or false? A percentage yield of more than 100% is possible if the reaction works especially well.

False. The maximum theoretical mass is the most that can ever be made, so percentage yield can never exceed 100%.

What are the steps to calculate the percentage yield of a product?

e.g. 4 g of product is made when the maximum theoretical mass is 5 g

1. Divide actual mass by maximum theoretical mass: $4 \div 5 = 0.8$
2. Multiply by 100: $0.8 \times 100$
3. Percentage yield $= 80\%$

What are the steps to find the mass of product actually made from the percentage yield?

e.g. percentage yield $= 80\%$, maximum theoretical mass $= 20$ g

1. Divide the percentage yield by 100: $80 \div 100 = 0.8$
2. Multiply by the maximum theoretical mass: $0.8 \times 20$
3. Mass actually produced $= 16$ g