Chemical reactions?

Question

what chemicals can you add together for a chemical reaction but then separate afterwards and end up with the same forms you started with?

Answer 1

2N + 3H2 <> 2NH3

The equilibrium reaction for ammonia production; runs both ways, with product making reactant and reactant making product.

Actually, Kenny, many, if not most reactions are equilibrium reactions.

Answer 2

Generally, entropy doesn't allow this - most reactions are not reversible.

Still, some are.