Endothermic & exothermic reversible reactions

• Reversable reactions can be exothermic and endothermic
• In reversable reactions, if the reaction is endothermic in one direction, it will be exothermic in the other
• The energy transferred from the surroundings by the endothermic reaction is equal to the energy transferred to the surroundings during the exothermic reaction
• An example of thermal decomposition is hydrated copper sulfate: hydrated copper sulfate ⇌ anhydrous copper sulfate + water
• If you heat blue hydrated copper(II) sulphate crystals, it drives the water off and leaves white anhydrous copper(II) sulfate powder. This is endothermic
• If you then add a couple of drops of water to the white powder you get the blue crystals back again. This is exothermic