A student monitors the reversible gas-phase reaction X(g)⇌2Y(g)\text{X(g)} \rightleftharpoons 2\text{Y(g)}X(g)⇌2Y(g) inside a sealed syringe at a constant temperature. Once the system has reached a state of dynamic equilibrium, which of the following statements is correct?
The rate of consumption of X\text{X}X is equal to the rate of consumption of Y\text{Y}Y.
The concentration of Y\text{Y}Y is equal to twice the concentration of X\text{X}X due to the 1:21:21:2 stoichiometric ratio.
The macroscopic properties of the mixture, such as pressure and colour intensity, remain constant because the rates of the forward and backward reactions are equal.
The system has stopped reacting, meaning the activation energy for both the forward and backward reactions has been reduced to zero.
25 exam-style questions on OCR GCSE Chemistry Equilibria. Each one has a worked solution and a mark scheme showing where the marks go.