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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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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It is also known as washing soda.
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.
$2 \mathrm{NaHCO}_3 \rightarrow \mathrm{Na}_2 \mathrm{CO}_3+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O}$
It is also known as baking soda.
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.
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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NCERT Chemistry Notes:
Sodium carbonate (washing soda) and sodium bicarbonate (baking soda) are separate substances with a range of uses and characteristics
Sodium Carbonate (Na2CO3):-
Sodium bicarbonate (NaHCO3) :-
Sodium carbonate, a white crystalline substance with the chemical formula Na2CO3, is also referred to as washing soda or soda ash.
Sodium carbonate finds application in the production of glass, as a water softener, in detergents and other cleaning goods, in papermaking, and in several chemical reactions.
Sodium bicarbonate, commonly known as baking soda, The chemical formula for sodium bicarbonate, or baking soda, is NaHCO3.
Solvay process
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