Question

Distinguish between baking soda and washing soda by heating

Answer 1

Here is your answer:
Baking powder on heating decomposes to give sodium carbonate, water and carbon dioxide according to the following equation

NaHCO3 → Na2CO3 +H2O +CO2

Washing soda (Na2CO3.10H2O) on the other hand, on heating below 373 K loses 9 molecules of water of crystallization and forms Sodium carbonate monohydrate (Na2CO3.H2O). On heating above 373 K, this monohydrate changes to anhydrous white powder called soda ash – Na2CO3 but does not decompose further.

Na2CO3.10H2O → Na2CO3.H2O + 9 H2O (Below 373 K)

Na2CO3.H2O → Na2CO3 + H2O (above 373 K)

Soda ash

Therefore baking soda decomposes on heating with evolution of CO2, while washing soda loses its water of crystallization and forms soda ash but there is no evolution of CO2.
Hope this helps you

Answer 2

Baking powder on heating decomposes to give sodium carbonate, water and carbon dioxide according to the following equation

NaHCO3 → Na2CO3 +H2O +CO2

Washing soda (Na2CO3.10H2O) on the other hand, on heating below 373 K loses 9 molecules of water of crystallization and forms Sodium carbonate monohydrate (Na2CO3.H2O). On heating above 373 K, this monohydrate changes to anhydrous white powder called soda ash – Na2CO3 but does not decompose further.

Na2CO3.10H2O → Na2CO3.H2O + 9 H2O (Below 373 K)

Na2CO3.H2O → Na2CO3 + H2O (above 373 K)

Soda ash

Therefore baking soda decomposes on heating with evolution of CO2, while washing soda loses its water of crystallization and forms soda ash but there is no evolution of CO2.