Question

One of the major constituents of baking powder is sodium hydrogen carbonate, the other constituent is:
(A) Hydrochloric acid
(B) Tartaric acid
(C) Acetic acid
(D) Sulphuric acid

Answer 1

Hint: Baking powder contains a base which is generally bicarbonate, a dry buffer and an acid salt. The acid salt is a weak acid which is responsible for reacting with the base and thus producing carbon dioxide, providing leavening to the mixture.

Complete step by step solution: We often use baking powder in cooking as a leavening agent. It is a dry mixture of carbonate or bicarbonate and a weak acid. To prevent the base and the acid to react a buffer (like corn starch) is added.
When baking powder is added in a batter or dough the acid-base reaction causes the release of carbon dioxide gas into the batter, causing bubbles in the wet mixture and thus leavening the batter.
The most commonly used baking powder contains sodium bicarbonate which is the base, a buffering agent and one more acid salt.
Sodium carbonate and the acid salts react in presence of water and produce carbon dioxide. We can write the reaction as-
\[NaHC{{O}_{3}}+{{H}^{+}}\to N{{a}^{+}}+C{{O}_{2}}+{{H}_{2}}O\]
Baking powder contains around 30% sodium bicarbonate, 5-12% monocalcium phosphate which is the buffering agent and 21-26% sodium aluminium sulphate which is the acid salt.
Commercial baking powder might also use sodium acid pyrophosphate instead of sodium aluminium sulphate. Also, a derivative of tartaric acid known as cream of tartar is used. Cream of tartar is $K{{C}_{4}}{{H}_{5}}{{O}_{6}}$.
We can understand from the above discussion that besides sodium bicarbonate, the other constituent of baking powder is tartaric acid.

Therefore, the correct answer is option [B] Tartaric acid.

Note: The acid used in the baking powder can either be fast-acting or slow acting. The fast-acting acid reacts with the wet baking mixture at room temperature whereas the slow-acting acid does not react with the mixture until the temperature is increased. Some common fast-acting acid used in baking powder is cream of tartar and monocalcium phosphate and examples of slow-acting acids are sodium aluminium sulphate, sodium aluminium phosphate etc.