Hydrogen can be used as a fuel. A company compares two routes to make hydrogen.
Route A: methane reacts with steam.
CH4+2H2O→CO2+4H2 \mathrm{CH_{4}} + 2\mathrm{H_{2}O} \rightarrow \mathrm{CO_{2}} + 4\mathrm{H_{2}} CH4+2H2O→CO2+4H2Route B: water is electrolysed.
2H2O→2H2+O2 2\mathrm{H_{2}O} \rightarrow 2\mathrm{H_{2}} + \mathrm{O_{2}} 2H2O→2H2+O2The table shows information about the two routes.
| Information | Route A | Route B |
|---|---|---|
| raw materials | methane (from natural gas) and water | water |
| conditions | 800 °C, nickel catalyst | room temperature, electric current |
| energy source | burning natural gas | electricity from wind turbines |
| percentage yield of hydrogen (%) | 75 | 98 |
| atom economy (%) | ? | 11.1 |
| other product | carbon dioxide, released into the air | oxygen, sold to hospitals |
| cost to make 1 kg of hydrogen (£) | 1.50 | 4.50 |
Calculate the atom economy of Route A.
Give your answer to 3 significant figures.
Relative atomic mass (Ar): H = 1.0 C = 12.0 O = 16.0
Atom economy = ...... %
Evaluate the two routes and recommend which route the company should use.
Use your answer to (a) and the information in the table.
57 exam-style questions on OCR GCSE Chemistry 5.1 Monitoring chemical reactions, covering 5.1.1 The technique of titration, 5.1.2 Theoretical mass, percentage yield and atom economy, 5.1.3 Concentration of a solution in mol/dm3, 5.1.4 Concentration calculations and titration results, 5.1.5 Molar gas volume and volumes of gases in reactions, and 5.1.6 Choosing a reaction pathway. Each one has a worked solution and a mark scheme showing where the marks go.