CBSE Class 10 Science 2018 · Paper 31(B) · Question 6(a)

Name: baking powder. Ingredients and their functions: 1. Sodium hydrogencarbonate (baking soda), ${\text{NaHCO}}_3$: on heating it gives off carbon dioxide, whose bubbles make the pakoras soft and crisp. 2. Tartaric acid, a mild edible acid: it reacts with the sodium hydrogencarbonate, so no bitter-tasting sodium carbonate is left; it removes the bitter taste. Equation (baking powder on heating): ${\text{NaHCO}}_3+{\text{H}}^{+}\stackrel{\text{heat}}{\to }{\text{CO}}_2+{\text{H}}_2\text{O}+$ sodium salt of the acid, the ${\text{H}}^{+}$ coming from the tartaric acid. Sodium hydrogencarbonate on its own decomposes on heating: $2{\text{NaHCO}}_3\stackrel{\text{heat}}{\to }{\text{Na}}_2{\text{CO}}_3+{\text{H}}_2\text{O}+{\text{CO}}_2$.