Question

Explain why the aqueous solution of sodium carbonate is alkaline?

Answer 1

Aqueous solution of Sodium carbonate is alkaline

• The aqueous solution of Sodium carbonate (${\mathrm{Na}}_2{\mathrm{CO}}_3$) is alkaline in nature.
• Because Sodium carbonate is a salt of a strong base and weak acid.
• When Sodium carbonate is dissolved in water it gets hydrolyzed and forms a weak acid Carbonic acid (${\mathrm{H}}_2{\mathrm{CO}}_3$) and a strong base Sodium hydroxide ($\mathrm{NaOH}$).
• Following is the reaction:
  $\underset{\mathrm{Sodium}\mathrm{Carbonate}}{{\mathrm{Na}}_2{\mathrm{CO}}_3(\mathrm{aq}.)}+\underset{\mathrm{Water}}{2{\mathrm{H}}_2\mathrm{O}}\left(\mathrm{l}\right)\to \underset{\mathrm{Carbonic}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{CO}}_3}\left(\mathrm{g}\right)+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}}(\mathrm{aq}.)$

Therefore, an aqueous solution of sodium carbonate is alkaline in nature.