Chemical equilibrium — Question 8

8

At equilibrium, the forward reaction rate equals the reverse reaction rate. Therefore, yellow chromate ions and orange dichromate ions are re-formed at the same rate at which they are broken down, so the colour remains constant because the [CrO₄^2–] and [Cr₂O₇^2–] remain constant.

• identifies that the forward reaction rate equals the reverse reaction rate at equilibrium [1 mark]

• explains that the colour remains constant because the [CrO₄^2–] and [Cr₂O₇^2–] remain constant [1 mark]