When one mole of blue hydrated copper(II) sulfate is heated, it forms white anhydrous copper(II) sulfate and water. This change takes in 78 kJ of energy from the surroundings.
The white solid is left to cool. Water is then added to it until one mole of the blue solid has formed again.
Which statement describes the energy transfer as the blue solid forms again?
78 kJ78\ \text{kJ}78 kJ is taken in from the surroundings, so the solid cools down
No energy is transferred, because adding water is only a physical change
78 kJ78\ \text{kJ}78 kJ is released to the surroundings, so the solid warms up
Less than 78 kJ78\ \text{kJ}78 kJ is released, because some energy stays stored in the solid
109 exam-style questions on AQA GCSE Chemistry 6.2 Reversible reactions and dynamic equilibrium, covering 6.2.1 Reversible reactions, 6.2.2 Energy changes and reversible reactions, 6.2.3 Equilibrium, 6.2.4 The effect of changing conditions on equilibrium, 6.2.5 The effect of changing concentration, 6.2.6 The effect of temperature changes on equilibrium, and 6.2.7 The effect of pressure changes on equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.