Exothermic and endothermic reactions

What is a good example of an exothermic reaction in one direction & exothermic in another

If you heat blue hydrated copper sulphate crystals it drives the water off and leaves white anhydrous copper sulfate powder (this is endothermic) If you add a couple of drops of water to the white powder you get blue crystals back again (this is exothermic) hydrated copper sulphate ----> anhydrous copper sulfate + water <------

If a reversible reaction is exothermic in one direction, what is it in the other direction & dhow does the energy change in these reactions?

it is endothermic in the opposite direction. it doesn't change! the same amount of energy is transferred in each case (energy absorbed in the endothermic reaction is equal to energy released during the exothermic reaction)

What is an endothermic reaction, give examples & what its everyday uses are?

An endothermic reaction is one that takes in energy from the surroundings (usually in the form of heat shown by a fall in temp) thermal decompositions (e.g. calcium carbonate decomposes to make quicklime) electrolysis, Some sports injury packs (they take in heat & the pack becomes v cold)

What is an exothermic reaction, give examples & what its everyday uses are?

An exothermic reaction is one that transfers energy to the surroundings (usually in the form of heat which is show by a temp rise) Combustion (burning fuels), many oxidation reactions and neutralisation (acid+alkali) include self-heating cans (eg for coffee) and hand warmers

When a chemical reaction occurs, how is energy involved?

When chemical reactions occur, energy is transferred to or from the surroundings