In 1892, Lord Rayleigh made samples of nitrogen in two ways:
method 1: removing oxygen, carbon dioxide and water vapour from air
method 2: decomposing ammonia
He found that nitrogen from method 1 was always slightly denser than nitrogen from method 2.
The table shows values based on his results, adjusted to room temperature and pressure.
| Method | Mass of 1.000 dm3\mathrm{dm^{3}}dm3 of gas in g |
|---|---|
| 1 (from air) | 1.1727 |
| 2 (from ammonia) | 1.1667 |
Rayleigh measured the mass of each sample several times. Give one reason why.
Explain why the gas from method 1 had a greater mass per dm3\mathrm{dm^{3}}dm3 than the gas from method 2.
Show that the mass of 1.000 dm3\mathrm{dm^{3}}dm3 of pure nitrogen, N2\mathrm{N_{2}}N2, is 1.1667 g. Relative formula mass: N2=28\mathrm{N_{2}} = 28N2=28. One mole of any gas occupies 24 dm3\mathrm{dm^{3}}dm3 at room temperature and pressure.
The gas from method 1 was a mixture of nitrogen and argon. Determine the percentage by volume of argon in this mixture. Relative atomic mass: Ar = 40. Give your answer to two significant figures.
Mendeleev published his periodic table in 1869. It did not contain group 0. Explain why.
38 exam-style questions on Edexcel GCSE Chemistry 7.3 Group 0, covering 7.3.1 The noble gases. Each one has a worked solution and a mark scheme showing where the marks go.