Question

A candle and a firework both can be ignited with a spark, but they release different amounts of energy as they burn. Compare and contrast the potential energy diagrams that would represent each of these burning processes.

Answer 1

OK, burning both the candles and the fireworks involve chemical reactions - the conversion of both substances to ash. So right away, you know that the reactants and the products of both reactions are different.

You also know that burning a candle and fireworks both release heat. The reaction is exothermic. That means that the reactants have a higher potential energy than the products. You also know that neither the candle nor the fireworks burn spontaneously - that the reactions won't go unless you've put in some energy in the form of a spark - so for both reactions your energy diagram should show an energy barrier.

The fireworks are more explosive than the candle - they release a lot more heat when ignited - so if you were drawing both energy curves in same diagram, the fireworks would start with more potential energy than the candle. They both go to the same product - ash - so both curves end up at the same energy.

Clear?