Baking soda (NaHCO₃) is commonly used in cooking. Which of the following statements about it is correct?

The correct option is: It reacts with acids to release carbon dioxide gas.

Let us understand why this statement is correct by analyzing the chemical properties of baking soda (sodium hydrogen carbonate, NaHCO₃) step-by-step:

1. Nature of Baking Soda:
Baking soda, with the chemical formula NaHCO₃, is a salt formed by the neutralization of a strong base (sodium hydroxide, NaOH) and a weak acid (carbonic acid, H₂CO₃). Because of this, it is a mild or weak basic (alkaline) salt, not a strong base. When dissolved in water, it undergoes hydrolysis to form a weakly basic solution with a pH greater than 7 (typically around 8.3). Therefore, options suggesting it is acidic (pH < 7) or a strong base are incorrect.

2. Reaction with Acids:
As a carbonate/hydrogen carbonate salt, baking soda readily reacts with acids (such as hydrochloric acid, acetic acid, etc.). When a hydrogen carbonate reacts with an acid, it undergoes a neutralization reaction that produces a salt, water, and carbon dioxide gas (CO₂).

The general word equation for this reaction is:
Metal hydrogen carbonate + Acid → Salt + Water + Carbon dioxide

The balanced chemical equation for the reaction of baking soda with a typical acid like hydrochloric acid (HCl) is:

$${\mathrm{NaHCO}}_3(s)+\mathrm{HCl}(\mathrm{aq})\to \mathrm{NaCl}(\mathrm{aq})+H_{2}O(l)+{\mathrm{CO}}_2(g)$$

3. Practical Application in Cooking:
This specific reaction is the scientific basis for using baking soda in cooking and baking. When baking soda is mixed with acidic ingredients (like lemon juice, buttermilk, or yogurt) in a batter, it reacts to release carbon dioxide bubbles. These trapped bubbles of CO₂ gas expand during heating, causing cakes, bread, and other baked goods to rise and become light and fluffy.