Reversible Reactions and Energy Changes
Unlike regular reactions that just go in one direction until everything's used up, reversible reactions can flip back and forth between reactants and products. Think of it like a two-way street where traffic can flow in both directions.
You'll spot these reactions by their special ⇌ symbol, which shows both forward and backward reactions happening simultaneously. The direction depends entirely on the conditions - heat might push it forward, whilst cold pushes it backward.
Here's something brilliant about energy: if a reversible reaction gives out energy (exothermic) going forward, it takes in exactly the same amount going backward (endothermic). The copper sulfate example shows this perfectly - adding heat removes water (endothermic), whilst adding water releases heat (exothermic).
Quick Check: Blue hydrated copper sulfate turns white when heated, but goes blue again when you add water!
