Question

Define the following term and answer the associated question :

Endothermic reaction: State the effect of an endothermic reaction on the surroundings. Also give an example of such a reaction.

Answer 1

Endothermic reaction: Endothermic reactions are the type of chemical reactions in which the reactants absorb heat energy from the surroundings to form products.

• During these reactions bond is formed and energy is absorbed from the surroundings giving a cooling effect.
• The general equation of this reaction is- A + B + Q kcal⇢ C + D

Let us understand it with an example.

• When ammonium chloride (NH₄Cl) is dissolved in water, an endothermic reaction takes place. The salt dissociates into ammonium (NH₄⁺) and chloride (Cl^–) ions.
• The chemical equation can be written as follows:

${\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)⟶{\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)–\mathrm{Heat}$