# When copper sulfate solution is mixed with excess anhydrous white copper sulfate powder in a sealed container, a reversible reaction occurs. Explain what happens to the rate of the forward and backward reactions over time, and describe the conditions that exist once dynamic equilibrium has been reached.

> Edexcel GCSE Chemistry (1CH0) — 4.2 Reversible reactions and equilibria · Explain · 4 marks

> Anhydrous copper sulfate is a white powder. When water is added, it forms blue hydrated copper sulfate. This reaction is reversible. A student places anhydrous copper sulfate in a sealed container with a small amount of water and observes the system over time.

## Mark scheme (4 marks)

1. The rate of the forward reaction starts high and decreases over time (as reactants are used up)
2. The rate of the backward reaction starts at zero/low and increases over time (as products build up)
3. At dynamic equilibrium, the rate of the forward reaction equals the rate of the backward reaction
4. At dynamic equilibrium, the concentrations of reactants and products remain constant (not equal)

## Key terms

- [reversible reaction](https://www.gradenine.co.uk/glossary/reversible-reaction)
- [dynamic equilibrium](https://www.gradenine.co.uk/glossary/dynamic-equilibrium)
- [backward reaction](https://www.gradenine.co.uk/glossary/backward-reaction)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/when-copper-sulfate-solution-is-mixed-0cc0b9d6) · Published by Druglandscape Ltd.