A manufacturer tests a batch process for making calcium hydroxide from calcium oxide and water.
CaO+H2O→Ca(OH)2\text{CaO} + \text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2CaO+H2O→Ca(OH)2
Calcium hydroxide is the desired product. The calcium oxide reacts completely and there are no unwanted side reactions.
| Measurement for the first batch | Value |
|---|---|
| Maximum theoretical mass of calcium hydroxide | 80.0 kg |
| Mass of calcium hydroxide collected after separation | 68.0 kg |
Calculate the percentage yield for the first batch.
The manufacturer replaces the separator with one that collects more of the calcium hydroxide after the reaction.
Explain why this change would increase the percentage yield but would not change the atom economy.
A second batch has the same maximum theoretical mass as the first batch. The new separator halves the mass of calcium hydroxide lost during separation.
Calculate the percentage yield for the second batch.
104 exam-style questions on AQA GCSE Chemistry 3.3 Yield and atom economy of chemical reactions, covering 3.3.1a Percentage yield, 3.3.1b Theoretical mass of a product, 3.3.2a Atom economy, and 3.3.2b Choosing a reaction pathway. Each one has a worked solution and a mark scheme showing where the marks go.