What the distinguish between exothermic and endothermic?

Answer 1

Endothermic reactions are reactions that create bonds between atoms, which means they require energy, so they take heat energy from its surroundings to create the bonds (meaning the reaction produces "cold"), and exothermic reactions are ones which break bonds between atoms, giving off energy and thus heat.

Answer 2

The words 'Endothermic ' and 'Exothermic' come from Classical Greece,

The moiety ; thermic; means heat.

The prefixes 'Exo ' means 'out of' and 'Endo' means ' in to'.

So for an Endothermic reaction it means 'heat is going in to'' in order to break the bonds.

For an Exothermic reaction in means 'heat is coming out' in order to form bonds.

As an example, when calcium carbonate is heated, heat is being driven in, in order to break bonds to form calcium oxide and carbon dioxide. So it is an ENDOTHERMIC reaction. The heat that you may feel from the Bunsen burner is 'waste' heat because it is not going in to break the bond, but some heat is going in!!!

Conversely, the neutralisation of HCl and NaOH. You mix the two together, without heating , yet the beaker feels warm. This is an EXOTHERMIC reaction as energy is released as the water bonds form.

Answer 3

An exothermic reaction releases heat to its surroundings, resulting in a temperature increase. On the other hand, an endothermic reaction absorbs heat from its surroundings, causing a temperature decrease.