Nitrogen dioxide, NO2\mathrm{NO_{2}}NO2, is a brown gas. Dinitrogen tetroxide, N2O4\mathrm{N_{2}O_{4}}N2O4, is a colourless gas.
2NO2(g)⇌N2O4(g) \mathrm{2NO_{2}(g) \rightleftharpoons N_{2}O_{4}(g)} 2NO2(g)⇌N2O4(g)The forward reaction is exothermic. A sealed tube containing an equilibrium mixture is placed in ice-cold water.
What is observed?
The mixture becomes darker, because the position moves to the left.
The mixture becomes paler, because the position moves to the right.
The mixture becomes paler, because the reaction stops in the cold.
The mixture becomes darker, because the gases are compressed.
47 exam-style questions on OCR GCSE Chemistry 5.3 Equilibria, covering 5.3.1 Reversible reactions and dynamic equilibrium and 5.3.2 Changing the position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.