Question

Give two examples of the following change occurring during a chemical reaction:

Formation of a precipitate

Answer 1

Chemical reaction- A chemical reaction is the change of a substance into a new one that has a different chemical identity.

• Some reactions are characterized by the formation of precipitates.
• Two examples of it are given below.

Formation of a precipitate-

• $\underset{\mathrm{silver}\mathrm{nitrate}}{{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{sodium}\mathrm{chloride}}{\mathrm{NaCl}\left(\mathrm{aq}\right)}\to \underset{\mathrm{silver}\mathrm{chloride}}{\mathrm{AgCl}(\downarrow )}+\underset{\mathrm{sodium}\mathrm{nitrate}}{{\mathrm{NaNO}}_3\left(\mathrm{aq}\right)}$
• In the above reaction silver nitrate is reacting with sodium chloride to form sodium nitrate and silver chloride as a precipitate.
• $\underset{\mathrm{Ferrous}\mathrm{sulphate}}{{\mathrm{FeSO}}_4\left(\mathrm{aq}\right)}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Ferrous}\mathrm{hydroxide}}{\mathrm{Fe}{\left(\mathrm{OH}\right)}_2\downarrow }+\underset{\mathrm{Sodium}\mathrm{sulphate}}{{\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)}$
• When ferrous sulfate solution is added to the Sodium hydroxide, a dirty green precipitate of Ferrous hydroxide is formed.