Question

72. Classify the chemical reactions into various types depending on the way the products are formed by giving suitable examples.

Answer 1

A Chemical Reaction is a process that occurs when two or more molecules interact to form a new product(s). The different types of chemical reactions are:

1. Combination reaction: The reaction in which two or more substances i.e., elements, compounds, or both combine to form one compound is known as combination reaction.

• Example: $\underset{\mathrm{Sodium}}{2\mathrm{Na}\left(\mathrm{s}\right)}+\underset{\mathrm{Chlorine}}{{\mathrm{Cl}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Sodium}\mathrm{chloride}}{2\mathrm{NaCl}\left(\mathrm{s}\right)}$

2. Decomposition reaction: A reaction in which a single compound breaks into two or simpler compounds is known as a decomposition reaction.

• Example: $\underset{\mathrm{Calcium}\mathrm{carbonate}}{{\mathrm{CaCO}}_3\left(\mathrm{s}\right)}\to \underset{\mathrm{Calcium}\mathrm{oxide}}{\mathrm{CaO}\left(\mathrm{s}\right)}+\underset{\mathrm{Carbon}\mathrm{dioxide}}{{\mathrm{CO}}_2\left(\mathrm{g}\right)}$

3. Displacement reaction: A chemical reaction in which a more reactive element displaces a less reactive element from its compound is known as displacement reaction.

• Example: $\underset{\mathrm{Zinc}}{\mathrm{Zn}\left(\mathrm{s}\right)}+\underset{\mathrm{Copper}\mathrm{sulphate}}{{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)}\to \underset{\mathrm{Zinc}\mathrm{sulphate}}{{\mathrm{ZnSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Copper}}{\mathrm{Cu}\left(\mathrm{s}\right)}$

4. Double displacement reaction: A chemical reaction in which ions get exchanged between two reactants that form a new compound is called a double displacement reaction.

• Example: $\underset{\mathrm{Barium}\mathrm{chloride}}{{\mathrm{BaCl}}_2\left(\mathrm{aq}\right)}+\underset{\mathrm{Sodium}\mathrm{sulphate}}{{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}\to \underset{\mathrm{Barium}\mathrm{sulphate}}{{\mathrm{BaSO}}_4\left(\mathrm{s}\right)}+\underset{\mathrm{Sodium}\mathrm{chloride}}{2\mathrm{NaCl}\left(\mathrm{aq}\right)}$

5. Precipitation reaction: A chemical reaction that involves the formation of an insoluble product (precipitate; solid) is called precipitation reaction.

• Example: $\underset{\mathrm{Sodium}\mathrm{chloride}}{\mathrm{NaCl}\left(\mathrm{aq}\right)}+\underset{\mathrm{Silver}\mathrm{nitrate}}{{\mathrm{AgNO}}_3}\left(\mathrm{aq}\right)\to \underset{\mathrm{Silver}\mathrm{chloride}}{\mathrm{AgCl}}\left(\mathrm{s}\right)+\underset{\mathrm{Sodium}\mathrm{nitrate}}{{\mathrm{NaNO}}_3}\left(\mathrm{aq}\right)$