Question

“Sodium hydrogen carbonate is a basic salt." Justify the statement. How is it converted into washing soda? Explain.

Answer 1

Hint:We know that Sodium hydrogen carbonate is a basic salt because its parent base is strong (NaOH) and parent acid is weak (\[{H_2}C{O_3}\]). When Sodium hydrogen carbonate is heated strongly, it produces sodium carbonate, water and carbon dioxide and \[N{a_2}C{O_3}\] by crystallization gives the washing soda.

Complete answer:
As we know that sodium hydrogen carbonate is a salt which is produced by the neutralization reaction between a strong base i.e. NaOH and a weak acid i.e. \[{H_2}C{O_3}\], Hence, we know that it is a basic salt.
When Sodium hydrogen carbonate is heated strongly, it produces sodium carbonate, water and carbon dioxide.
It involves following reactions:
\[NaHC{O_3} + heat \to N{a_2}C{O_3} + {H_2}O + C{O_2}\]
\[N{a_2}C{O_3}\] by crystallization gives \[N{a_2}C{O_3}.10{H_2}O\] (washing soda). This \[N{a_2}C{O_3}.10{H_2}O\], sodium carbonate so obtained upon crystallization is washing soda.
Also, we know that Sodium hydrogen carbonate ($NaHCO3$) is a basic salt because it is made up of a weak acid and strong base.
Heating of baking soda; recrystallization of sodium carbonate gives washing soda. It is also a basic salt.
\[\left[ {baking\,soda} \right]\left( {heat} \right) \to \left[ {Sodium\,carbonate} \right] + \left[ {Water} \right] + \left[ {Carbon{\text{ }}Dioxide} \right]\]
We have seen above that sodium carbonate can be obtained by
\[N{a_2}C{O_3} + 10{H_2}O \to N{a_2}C{O_3}10{H_2}O\]

Note:
Washing soda is a salt of carbonic acid, a chemical that produces a wide range of salts collectively known as carbonates. The sodium carbonate softens water helping other cleaning ingredients lift soil from the fabrics and suspend the soil in the wash water. The washing soda binds to the minerals and thus makes water hard and allows the detergent to be absorbed into fibres properly in order to clean clothes. Also, we should note that washing soda should not be confused with baking soda, although the two compounds are closely related.