Chapter 2 · Question 13

How is baking soda prepared? Write its chemical equation for heating during cooking. Explain the difference between baking soda and baking powder, and how baking soda is useful as an antacid.

Q13

How is baking soda prepared? Write its chemical equation for heating during cooking. Explain the difference between baking soda and baking powder, and how baking soda is useful as an antacid.

Answer Revealed

Direct Answer:

Baking soda (sodium hydrogencarbonate,

\text{NaHCO}_3

) is produced from sodium chloride:

\text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 + \text{NH}_3 \rightarrow \text{NH}_4\text{Cl} + \text{NaHCO}_3

. On heating during cooking, it decomposes:

2\text{NaHCO}_3 \xrightarrow{\text{Heat}} \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2

. The released CO₂ makes bread and cakes rise. Baking powder is a mixture of baking soda and a mild edible acid (like tartaric acid) — when heated or mixed with water, the acid reacts with

\text{NaHCO}_3

to produce CO₂ more efficiently:

\text{NaHCO}_3 + \text{H}^+ \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{sodium salt}

. As an antacid, baking soda neutralises excess stomach acid because it is a mild, non-corrosive basic salt.

Simple Explanation

Baking soda (

\text{NaHCO}_3

) is the magic white powder that makes your cake spongy. When heated, it breaks down and releases carbon dioxide gas — those bubbles get trapped in the batter and push it up. But baking soda alone can leave a bitter taste, so baking powder is a better option: it is baking soda mixed with a food-grade acid (tartaric acid). The acid helps release CO₂ more cleanly. For stomach acidity, a pinch of baking soda works as a quick antacid — it is a mild base that calms the excess acid in your stomach, which is why it is an ingredient in many antacid tablets.

Exam-Ready Structure

Baking soda (sodium hydrogencarbonate) is one of the most versatile chemicals derived from common salt, with applications spanning cooking, medicine, and fire safety. 1. Chemical identity: Chemical name — sodium hydrogencarbonate; formula —

\text{NaHCO}_3

. It is a mild, non-corrosive basic salt. 2. Preparation: Produced using sodium chloride (common salt) as one of the raw materials, along with water, carbon dioxide, and ammonia:

\text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 + \text{NH}_3 \rightarrow \text{NH}_4\text{Cl} + \text{NaHCO}_3

. 3. Action on heating (during cooking):

2\text{NaHCO}_3 \xrightarrow{\text{Heat}} \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2

. The carbon dioxide gas released during heating causes bread, cake, pakoras, etc. to rise and become soft and spongy. The sodium carbonate (

\text{Na}_2\text{CO}_3

) produced on heating is used to prepare washing soda. 4. Baking powder vs baking soda: (a) Baking soda is pure

\text{NaHCO}_3

. On heating alone, it produces

\text{Na}_2\text{CO}_3

, which can give a slightly bitter taste. (b) Baking powder is a mixture of baking soda and a mild edible acid such as tartaric acid. (c) When baking powder is heated or mixed with water, the acid provides

\text{H}^+

ions that react with

\text{NaHCO}_3

\text{NaHCO}_3 + \text{H}^+ \rightarrow \text{CO}_2 + \text{H}_2\text{O} + \text{Sodium salt of acid}

. (d) The advantage: the acid neutralises the

\text{Na}_2\text{CO}_3

that would otherwise form, preventing the bitter aftertaste. 5. As an antacid: Baking soda is alkaline (it gave a basic pH in Activity 2.14). Being a mild base, it neutralises excess hydrochloric acid in the stomach, providing relief from acidity and indigestion. 6. Additional use: Soda-acid fire extinguishers use the reaction of

\text{NaHCO}_3

with dilute

\text{H}_2\text{SO}_4

to produce a jet of CO₂ that extinguishes fire.

Key Points

Baking soda = $\text{NaHCO}_3$ (sodium hydrogencarbonate), a mild non-corrosive basic salt
Preparation: $\text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 + \text{NH}_3 \rightarrow \text{NH}_4\text{Cl} + \text{NaHCO}_3$
On heating: $2\text{NaHCO}_3 \xrightarrow{\text{Heat}} \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2$ (CO₂ makes food rise)
Baking powder = baking soda + mild edible acid (tartaric acid) — more efficient CO₂ release, no bitter taste
Antacid: neutralises excess stomach acid; fire extinguisher: produces CO₂ to put out fire

Common Mistakes

Confusing baking soda ( $\text{NaHCO}_3$ ) with washing soda ( $\text{Na}_2\text{CO}_3$ ) — baking soda has hydrogen in its formula; washing soda does not
Thinking baking soda and baking powder are the same — baking powder contains an added acid

How is baking soda prepared? Write its chemical equation for heating during cooking. Explain the difference between baking soda and baking powder, and how baking soda is useful as an antacid.