Sodium Carbonate and Sodium bicarbonate

Sodium bicarbonate, also referred to as baking soda, and sodium carbonate, also known as washing soda, are two different but equally useful substances.

Sodium carbonate (Na₂CO₃) is a white, crystalline solid, mostly produced by the Solvay Process. It is also present in hydrated forms such as decahydrate (Na₂CO₃·10H₂O). It becomes anhydrous soda ash at higher temperatures and is very soluble in water. This material is extensively utilized as an analytical reagent in laboratories and also in the laundering, glass-making, and water-softening industries. It is used in the manufacture of glass, soap, borax, and caustic soda also in paper, paints, and textile industries.

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This Story also Contains

1. Sodium Carbonate
2. Sodium Bicarbonate
3. Some Solved Examples
4. Conclusion

On the other hand, Sodium bicarbonate(NaHCO₃)is the result of the reaction between carbon dioxide and a saturated solution of sodium carbonate. Its basic properties in an aqueous solution are revealed when it appears as a white, crystalline solid with partial solubility in water. When heated, it breaks down to release carbon dioxide and becomes sodium carbonate. Sodium bicarbonate has several useful applications, such as reducing stomach acidity and being a main component of baking powder, fire extinguishers, and fizzy beverages. It is used in medicines as a mild antiseptic for skin infections. These materials demonstrate the many applications of sodium compounds in industry, medicine, and domestic products, highlighting their essential roles in modern chemistry and daily life.

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Sodium Carbonate

It is also known as washing soda.

Preparation

Sodium carbonate is generally prepared by the Solvay Process. In this process, the advantage is taken of the low solubility of sodium hydrogen carbonate whereby it gets precipitated in the reaction of sodium chloride with ammonium hydrogen carbonate. The latter is prepared by passing CO₂ to a concentrated solution of sodium chloride saturated with ammonia, where ammonium carbonate followed by ammonium hydrogen carbonate is formed. The equations for the complete process may be written as:

$\begin{aligned} & 2 \mathrm{NH}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2 \rightarrow\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3 \\ & \left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2 \rightarrow 2 \mathrm{NH}_4 \mathrm{HCO}_3 \\ & \mathrm{NH}_4 \mathrm{HCO}_3+\mathrm{NaCl} \rightarrow \mathrm{NH}_4 \mathrm{Cl}+\mathrm{NaHCO}_3\end{aligned}$

Sodium hydrogen carbonate crystal separates. These are heated to give sodium carbonate.

$2 \mathrm{NaHCO}_3 \rightarrow \mathrm{Na}_2 \mathrm{CO}_3+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O}$

Properties

• Sodium carbonate is a white crystalline solid which exists as a decahydrate,Na₂CO₃·10H₂O. This is also called washing soda.
• It is readily soluble in water.
• On heating, the decahydrate loses its water of crystallization to form monohydrate.
• Above 373K, the monohydrate becomes completely anhydrous and changes to a white powder called soda ash.

Uses

• It is used in water softening, laundering, and cleaning.
• It is used in the manufacture of glass, soap, borax, and caustic soda.
• It is used in paper, paints, and textile industries.
• It is an important laboratory reagent both in qualitative and quantitative analysis.

Sodium Bicarbonate

It is also known as baking soda.

Preparation

It is prepared by passing carbon dioxide through a saturated solution of sodium carbonate as follows:

$\mathrm{Na}_2 \mathrm{CO}_3+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{NaHCO}$
Sodium bicarbonate can be easily precipitated from here as it is less soluble in water.

Properties

• It is a white crystalline solid partially soluble in water and its aqueous solution is basic. NaHCO₃ gives yellow colour with methyl red or methyl orange but no colour with HPH i.e., phenolphthalein.
• On heating at 100^oC, it decomposes into Na₂CO₃ with the evolution of CO₂.
• With zinc sulphate, it forms normal zinc carbonate.
  
  $\mathrm{ZnSO}_4+2 \mathrm{NaHCO}_3 \longrightarrow \mathrm{ZnCO}_3+\mathrm{Na}_2 \mathrm{SO}_4+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2$
• It reacts with dilute acids as follows:
  $\mathrm{NaHCO} 3+\mathrm{HCl} \longrightarrow \mathrm{NaCl}+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2$

Uses

• It is used to remove acidity in the stomach and in the making of baking powder (Sodium bicarbonate+potassium hydrogen tartrate).
• It is used in fire extinguishers.
• It is used in medicines as a mild antiseptic for skin infections.
• It is used in making effervescent drinks.

Recommended topic video on(Sodium Carbonate and Sodium Bicarbonate)

Some Solved Examples

Q.1 A hydrated solid X on heating initially gives a monohydrated compound Y. The compound Y upon heating above 373K forms an anhydrous white powder Z.The compounds X and Z respectively are :

1) Washing soda and soda ash.

2) Baking soda and dead burnt plaster.

3) Washing soda and dead burnt plaster.

4) Baking soda and soda ash.

Solution:

As we learned

Na₂CO₃ crystallizes from water as decahydrate, called Washing soda, which effloresces on exposure to dry air forming monohydrate. On heating above 373K, the monohydrate becomes completely dehydrated to form anhydrous salt which is called soda ash. The reactions involved are depicted below$\mathrm{Na}_2 \mathrm{CO}_3 \cdot 10 \mathrm{H}_2 \mathrm{O}(\mathrm{s}) \xrightarrow{\Delta} \mathrm{Na}_2 \mathrm{CO}_3 \cdot \mathrm{H}_2 \mathrm{O}(\mathrm{s}) \underset{T>373 \mathrm{k}}{\Delta} \mathrm{Na}_2 \mathrm{CO}_3(\mathrm{~s})$

Hence, the answer is the option (1).

Q.2 By product in the formation of Na₂CO₃ by Solvay process is :

1) NaCl

2) NH₃

3) NH₄OH

4) CaCl₂

Solution:

As we learned,

Manufacture of Na₂CO₃ by Solvay process -

Brine (NaCl), ammonia, and carbon dioxide are used as raw materials and calcium chloride is formed as a by-product

The reactions are given below:

$\begin{aligned} & \mathrm{NH}_3+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{NH}_4 \mathrm{HCO}_3 \\ & \mathrm{NH}_4 \mathrm{HCO}_3+\mathrm{NaCl}^{30^{-c}} \mathrm{NaHCO}_3 \downarrow+\mathrm{NH}_4 \mathrm{Cl} \\ & \mathrm{NaHCO}_3 \xrightarrow{250 \mathrm{C}} \mathrm{Na}_2 \mathrm{CO}_3+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2 \\ & 2 \mathrm{NH}_4 \mathrm{Cl}+\mathrm{Ca}(\mathrm{OH})_2 \rightarrow \mathrm{CaCl}_2+2 \mathrm{H}_2 \mathrm{O}+2 \mathrm{NH}_3\end{aligned}$

Hence, the answer is the option (4).

Q 3. When decahydrate of washing soda is treated with dry air, the product formed in the given process is :

1) NaHCO₃.7H₂O

2) NaHCO₃.8H₂O

3) NaHCO₃.2H₂O

4) NaHCO₃.H₂O

Solution:

As we learned,

Na₂CO₃ crystallizes from water as a decahydrate. Upon exposure to dry air, it forms monohydrate

$\mathrm{Na}_2 \mathrm{CO}_3 \cdot 10 \mathrm{H}_2 \mathrm{O} \xrightarrow{\text { dry air }} \mathrm{Na}_2 \mathrm{CO}_3 \mathrm{H}_2 \mathrm{O}+9 \mathrm{H}_2 \mathrm{O}$

Hence, the answer is the option (4).

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Conclusion

Sodium carbonate (washing soda) and sodium bicarbonate (baking soda) are separate substances with a range of uses and characteristics

Sodium Carbonate (Na₂CO₃):-

• Preparation: Generally produced by the Solvay Process, which combines ammonium hydrogen carbonate and sodium chloride in processes.
• Properties: It is a crystalline white solid that dissolves in water; it is typically found as decahydrate or Na₂CO₃·10H₂O. When heated, it loses water molecules and becomes anhydrous soda ash.
• Uses: Often used as a reagent in laboratory analyses, water softening, laundry, glass manufacturing, and soap production.

Sodium bicarbonate (NaHCO₃) :-

• Preparation: Produced by treating carbon dioxide with a sodium carbonate saturated solution.
• Characteristics: a white, crystalline solid that is somewhat soluble in water and forms a basic solution. At 100°C, it breaks down into sodium carbonate and releases carbon dioxide.
• Uses: Frequently used as an ingredient in baking powder, fire extinguishers, and fizzy drinks to counteract stomach acidity. Additionally employed as a mild antiseptic in medical applications.