Question

How would you distinguish between baking powder and washing soda by heating?

Answer 1

Baking powder:-

• It is a mixture of edible acid-like tartaric acid Sodium hydrogen carbonate.
• It is commonly used in cake-making, as it is a raising agent.
• It is made up of an alkali, Bicarbonate of soda, acid, cream of tartar, and a filler like cornflour or rice flour, that absorbs moisture.
• Carbon dioxide is produced and bubbles are formed that cause the mixture to expand, as the powder is activated when liquid is added.
• It has a chemical formula of ${\mathrm{NaHCO}}_3$

Washing soda:-

• Washing soda is a whitish and odourless powder in nature.
• Its chemical formula is Sodium bicarbonate${\mathrm{Na}}_2{\mathrm{CO}}_3$
• It absorbs moisture in the air as it is hygroscopic.
• It creates a strongly alkaline water solution, as it is extremely soluble in water.

Distinguish between Baking powder and Washing soda:-

• When baking soda is heated, Sodium bicarbonate, carbon dioxide, and water vapor is formed.
• The Carbon dioxide, extinguishes a blazing matchstick quickly.
• The complete reaction is:

$\underset{\mathrm{Sodium}\mathrm{hydrogen}\mathrm{carbonate}}{2{\mathrm{NaHCO}}_3\left(\mathrm{s}\right)}\stackrel{\mathrm{Heat}}{\to }\underset{\mathrm{Sodium}\mathrm{bicarbonate}}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}+{\mathrm{CO}}_2\left(\mathrm{g}\right)+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)}$

• When Washing soda is heated, it does not produce Carbon dioxide, but loses water of crystallization.
• the complete reaction is:

$\underset{\mathrm{Sodium}\mathrm{bicarbonate}}{{\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)}\stackrel{\mathrm{Heat}}{\to }\underset{\mathrm{Sodium}\mathrm{bicarbonate}}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}+\underset{\mathrm{Water}}{10{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)}$

Therefore, when baking powder ${\mathrm{NaHCO}}_3$ and washing powder ${\mathrm{Na}}_2{\mathrm{CO}}_3$ are both heated, baking powder produces Carbon dioxide but washing soda does not.