# 10.18 Describe two important uses of each of the following : (i) caustic soda (ii) sodium carbonate (iii) quicklime.

Answers (2)

(i) Caustic Soda-

The chemical name is sodium hydroxide ($NaOH$). Sodium hydroxide is generally prepared commercially by the electrolysis of sodium chloride in Castner-Kellner cell.

Uses-

•  the manufacture of soap, paper, artificial silk and a number of chemicals
•  in the purification of bauxite,
•  in the textile industries for mercerising cotton fabrics
•  for the preparation of pure fats and oils, and
•  as a laboratory reagent.

(ii) Sodium Carbonate-

The common name is washing soda ($Na_{2}CO_{3}$).Sodium carbonate is generally prepared by Solvay Process.

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

(iii) Quick lime-

The chemical name is calcium oxide and the formula is $CaO$. It is prepared on a commercial scale by heating limestone (CaCO3) in a rotary kiln at 1070-1270 K ( $CaCO_{3}\rightleftharpoons CaO+CO_{2}$)

Uses-

•  It is an important primary material for manufacturing cement and is the cheapest form of alkali.
•  It is used in the manufacture of sodium carbonate from caustic soda.
• It is employed in the purification of sugar and in the manufacture of dye stuffs.

It is an important primary material for manufacturing cement and is cheapest form of alkali

Which is used in the manufacturing of sodium carbonate from caustic soda

Employed in the purification of sugar and in the manufacture of dye stuffs

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