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Sodium Carbonate and Sodium Bicarbonate - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:35 AM | #JEE Main

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  • 19 Questions around this concept.

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Number of water molecules in washing soda and soda ash respectively are:

 

NaHCO_{3} is used in baking powder because:

Sodium carbonate is manufactured by solvay process. The product which can be recycled are-

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Sodium Carbonate and Sodium Bicarbonate

Sodium Carbonate
It is also known as washing soda.

Preparation
Sodium carbonate is generally prepared by 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 CO_2 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{array}{l}{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{array}

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 crystallisation 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{N} \mathrm{a}_{2} \mathrm{CO}_{3}+\mathrm{CO}_{2}+\mathrm{H_{2}} \mathrm{O} \rightarrow \mathrm{2NaHCO}_{3}
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 ar 100oC, it decomposes into Na2CO3 with the evolution of CO2.
  • With zinc sulphate, it forms normal zinc carbonate.

    \begin{array}{r}{\mathrm{ZnSO}_{4}+2 \mathrm{NaHCO}_{3} \longrightarrow \mathrm{ZnCO}_{3}+\mathrm{Na}_{2} \mathrm{SO_{4}\: +\: H_{2}} \mathrm{O}+\mathrm{CO}_{2}}\end{array}
     
  • 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 bicarbonare+potassium hydrogen tartarate).
  • 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.

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