is the maximum calculated mass of product expected to form from a given mass of reactants

is the actual amount of product obtained from a chemical reaction

is the actual yield (mass of product obtained) divided by the theoretical yield (maximum mass of product possible), as a percentage

is the percentage, by relative mass, of reactants that are converted into useful products

is a chemical product that is desired or valuable

Percentage yield and atom economy

Chemistry

In the Rates and energy changes unit, pupils learned about how energy changes are always involved in reaction, along with a range of methods for measuring and comparing rates of reaction using properties of reactants and/or products.

Industrial chemistry

Maximum calculated mass of product expected to form in a reaction.

Amount of product obtained from a chemical reaction.

Percentage of reactants converted into useful products.

Match the following terms to the correct definitions.

During an experiment, a pupil produces 3.25 g of magnesium oxide. The theoretical yield of magnesium oxide is 4.00 g.
Calculate the percentage yield. Give your answer to 3 s.f.

All the reactants are used in the reaction.

Why might the percentage yield of a reaction not be 100%?

Calculate the theoretical yield of magnesium oxide when 2.40 g of magnesium reacts with excess oxygen. Give your answer to 3 s.f.
2Mg + O₂ → 2MgO
Relative atomic masses (Ar): Mg = 24; O = 16.

It is a measure of the efficiency of how a reaction uses its reactants.

It shows how actual yield compares to theoretical yield.

Which of the following statements about atom economy are correct?

Calculate the percentage atom economy of the reaction below, when hydrogen is the useful product. Give your answer to 3 s.f.
2H₂O → O₂ + 2H₂
Relative atomic masses (Ar): H = 1; O = 16. 

Three beads are red and seven beads are green. What percentage of the beads are green?

Balance the following chemical equation:
CH₄ + O₂ → H₂O + CO₂ 

Calculate the relative formula mass (Mr) of calcium carbonate, CaCO₃. 
Relative atomic masses (Ar): Ca = 40; C = 12; O = 16.

The ratio of magnesium to magnesium oxide is 1 : 1

The ratio of magnesium oxide to oxygen is 1 : 2

The ratio of oxygen to magnesium is 1 : 2

The ratio of oxygen to magnesium oxide is 2 : 1

Which of the following statements about the equation below are correct?
2Mg + O₂ → 2MgO

When magnesium reacts with oxygen in the air to form magnesium oxide, magnesium is the limiting factor. There is more oxygen present than is needed, so we say that the oxygen is in {{}}.

Calculate the mass of 0.5 mol of magnesium. Give your answer to 2 s.f.
Relative atomic mass (Ar) of Mg = 24. 

This lesson will be removed by end of Summer Term 2025.

Percentage yield and atom economy

Lesson outcome

This lesson will be removed by end of Summer Term 2025.