Q. When washing soda is heated:

1653 213 AFMCAFMC 2005 Report Error

A

$CO$ is released

B

$CO + C O_{2}$ is released

C

$C O_{2}$ is released

D

water vapour is released

Solution:

Washing soda is sodium carbonate decahydrate $(N a_{2} C O_{3} \cdot 10 H_{2} O)$ . It is an efflorescent substance i.e., give out nine water molecules of crystallization on keeping in air
$N a_{2} C O_{3} \cdot 10 H_{2} O air Sodium carbonate monohydrate N a_{2} C O_{3} \cdot H_{2} O + 9 H_{2} O$
But on heating it losses all water molecules to form anhydrous sodium carbonate or soda ash
$N a_{2} C O_{3} \cdot 10 H_{2} O Δ (Soda ash) N a_{2} C O_{3} + 10 H_{2} O$