Question

Write about hard water and soft water. [2 marks]

Answer 1

• Hard water contains high amount of dissolved salts such as ${\mathrm{MgSO}}_4$, ${\mathrm{MgCl}}_2$, $\mathrm{Mg}{\left({\mathrm{HCO}}_3\right)}_2$,${\mathrm{CaSO}}_4$, ${\mathrm{CaCl}}_2$, and $\mathrm{Ca}{\left({\mathrm{HCO}}_3\right)}_2$.(0.5 mark)
• When combined with soap, hard water develops a thin layer (precipitates of the metal ions) called ‘scum’. (0.5 mark)
• Soft water has very little dissolved salts. (0.5 mark)
• Soft water doesn't forms ‘scum’. (0.5 mark)