Endothermic, Exothermic And Reversible Reactions (T2)

Question 0

Describe endothermic reactions..

Answer 0

Endothermic reactions take in energy from the surroundings.

The energy is usually transferred as heat energy, so the surroundings get colder.

Eg:

Electrolysis
Reaction between ethanoic acid and sodium carbonate
Thermal decomposition of calcium carbonate in a blast furnace

Question 1

Describe exothermic reactions…

Answer 1

Exothermic reactions ranger energy to the surroundings.

The energy is usually transferred as heat energy.

Eg:
Burning
Neutralisation reactions between acids and alkalis
The reaction between water and calcium oxide

Question 2

Describe reversible reactions using ammonium chloride as an example..

Answer 2

Reversible reactions are when the products can react to remake the original reactants.

Eg:

ammonium chloride (»arrow symbol«) Ammonia + hydrogen chloride

Ammonium chloride (a white solid) can break down to form ammonia and hydrogen chloride.

Ammonia and hydrogen chloride (colourless gases) can react to form ammonium chloride again.

Question 3

Describe a reversible reaction that is often used to test for water…

Answer 3

Anhydrous copper (II) sulphate + water (»«) blue hydrated copper (II) sulphate

This reaction is used to test for water as the white solid turns blue in the presence of water

Question 4

If the forward reaction is exothermic, the reverse reaction is…

Answer 4

Endothermic