Question

A chemical compound $\text{'}\mathrm{X}\text{'}$ is used in the soap and glass industry. It is prepared from brine.

(a) Write the chemical name, common name and chemical formula of $\text{'}\mathrm{X}\text{'}$.

(b) Write the equation involved in its preparation.

(c) What happens when it is treated with water-containing $\mathrm{Ca}$ or $\mathrm{Mg}$ salts?

Answer 1

(a)The chemical name is Sodium carbonate. Its common name is Washing Soda. The chemical formula of the compound in its hydrated form is${\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}$.

(b)The equation involved in its preparation are:

$\mathrm{NaCl}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{NH}}_3\left(\mathrm{aq}\right)\to {\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+{\mathrm{NaHCO}}_3\left(\mathrm{aq}\right)$

$2\mathrm{NaHCO}\left(\mathrm{aq}\right)\to {\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$

${\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{aq}\right)+10{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right)$

(c) Washing Soda helps in removing permanent hardness from water. It forms insoluble $\mathrm{Ca}$ or $\mathrm{Mg}$ salts in the form of scum when it is treated with water containing $\mathrm{Ca}$ or $\mathrm{Mg}$ salts.