Percentage Yield Flashcards

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What is meant by the yield of a chemical reaction?

The yield is the amount of product you actually get from a reaction.

What is percentage yield?

Percentage yield compares the amount of product you actually get with the maximum you could get, then multiplies by 100.

What is the formula for percentage yield?

Percentage yield = (actual yield ÷ theoretical yield) × 100.

What is the actual yield in a reaction?

The actual yield is the mass of product you really obtain in the experiment.

What is the theoretical yield in a reaction?

The theoretical yield is the maximum mass of product you should get, worked out from the balanced equation.

Give two reasons why percentage yield is usually less than 100%.

Some reactants do not fully react, and some product is lost when it is separated, transferred, or purified.

Why is a high percentage yield important in industry?

A high percentage yield means less waste and more product from the same reactants, so the process is cheaper and more efficient.

A reaction should make 20 g of a product, but only 15 g is obtained. What is the percentage yield?

Percentage yield = (15 g ÷ 20 g) × 100 = 75%.

What does a percentage yield of 100% tell you about a reaction?

It shows that the actual yield is equal to the theoretical yield, so, based on the data, no product was lost.

What might a percentage yield of more than 100% suggest?

It suggests there is an error, such as the product being wet or mixed with impurities, which makes its mass seem too high.

Why must you use the same units for both yields when calculating percentage yield?

You must measure both yields in the same unit, such as grams, so you can compare them fairly in the calculation.