A reversible reaction is started in a sealed flask with only the reactants present. The table shows the rates of the forward and reverse reactions at different times.
| Time (s) | Rate of forward reaction (arbitrary units) | Rate of reverse reaction (arbitrary units) |
|---|---|---|
| 0 | 9.0 | 0.0 |
| 20 | 6.1 | 2.3 |
| 40 | 4.6 | 3.6 |
| 60 | 4.2 | 4.2 |
| 80 | 4.2 | 4.2 |
| 100 | 4.2 | 4.2 |
Which statement is correct?
At 60 s, both the forward and reverse reactions have stopped.
At 80 s, the concentrations of reactants and products are equal.
At 100 s, the reverse reaction is faster than it was at 60 s.
At 40 s, the concentrations of the reactants are still decreasing.
124 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.