Chemistry 0620 · IGCSE · Reversible reactions and equilibrium
Reversible reactions and equilibrium — practice question
Dinitrogen tetroxide, N$_2$O$_4$, breaks down to form nitrogen dioxide, NO$_2$. This reaction can go in both directions. $\text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g)$ (colourless gas ⇌ brown gas). A gas syringe holding a mixture of dinitrogen tetroxide and nitrogen dioxide gases was sealed and then heated. Once equilibrium was reached, the mixture had a pale brown colour.
(a)[2]
State the meaning of the term equilibrium.
(b(i))[1]
Explain why the mixture first turns a darker brown.
(b(ii))[1]
Explain why equilibrium moves to the left.
(c(i))[1]
State how the position of equilibrium changes when the temperature of the mixture is increased.
(c(ii))[2]
State how the rate of the forward reaction and the rate of the backward reaction change when the temperature of the mixture is increased.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “forward reaction rate is equal to reverse reaction rate” …