Question

Identify the type of chemical reaction in the following statements and define each of them:
(a) Digestion of food in our body

(b) Rusting of iron.

(c) Heating of manganese dioxide with aluminum powder

(d) Blue color of copper sulfate solution disappears when iron filings are added to it.

(e) Dilute hydrochloric acid is added to sodium hydroxide solution to form sodium chloride and water.

Answer 1

(a) Digestion of food in our body

1. The reaction in which simple substances splits into two or more simple substances under suitable conditions is a decomposition reaction.
2. The digestion of food in our body is accompanied by a number of decomposition reactions.
3. The carbohydrates, fats, proteins, etc. are the major constituents of our food.
4. They decompose to form a number of simpler substances which further react releasing a large amount of energy.
5. It keeps our body working.

(b) Rusting of iron

Oxidation reaction:

1. The addition of oxygen to a substance or removal of hydrogen from a substance in a chemical reaction is known as an oxidation reaction.
2. The chemical formula for rust is ${\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O}$ known as iron oxide or ferric oxide.
3. Rusting of iron is an oxidation reaction.

(c) Heating of manganese dioxide with aluminum powder

Displacement reaction:

1. The chemical reaction in which a more reactive element takes the position or place of another less element present in the compound.
2. On heating manganese dioxide with aluminum powder, we observe aluminum displaces manganese from manganese dioxide $\left({\mathrm{MnO}}_2\right)$.
3. Chemical reaction on heating of manganese dioxide with aluminum powder is a displacement reaction.

The chemical reaction involves;

$4\mathrm{Al}\left(\mathrm{s}\right)+3{\mathrm{MnO}}_2\left(\mathrm{s}\right)\stackrel{\mathrm{heat}}{\to }2{\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+3\mathrm{Mn}\left(\mathrm{s}\right)$

(d) Blue color of copper sulfate solution disappears when iron filings are added

Displacement reaction:

1. The chemical reaction in which a more reactive element takes the position or place of another less element present in the compound.
2. The blue color of the copper sulfate solution disappears because iron displaces copper from the copper sulfate $\left({\mathrm{CuSO}}_4\right)$ solution, as it is more reactive than copper.
3. The blue color of copper sulfate solution disappears when iron filings are added to it due to displacement reaction.
4. Chemical reaction when iron nails are added to copper sulfate solution.

The chemical reaction involves;

$\mathrm{Fe}\left(\mathrm{s}\right)+{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)\to \mathrm{Cu}\left(\mathrm{s}\right)+{\mathrm{FeSO}}_4\left(\mathrm{aq}\right)$

(e) Dilute hydrochloric acid is added to sodium hydroxide solution to form sodium chloride and water.

Neutralization reaction:

1. When an acid reacts with a base to form a salt and water, it is known as a neutralization reaction.
2. Dilute hydrochloric acid is added to sodium hydroxide solution to form sodium chloride(Common salt) and water due to a neutralization reaction

Reaction involved:

$\mathrm{HCl}\left(\mathrm{aq}\right)+\mathrm{NaOH}\left(\mathrm{aq}\right)\to \mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)$

Hence, these are the type of chemical reactions in the following statements and definitions of each of them.