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Question

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Discuss the manufacture of sodium carbonate with a suitable flow diagram.

Solution

Now-a-days sodium carbonate is manufactured on a large-scale by Solvay ammonia process and involves the following steps:

(a) Carbon dioxide obtained from limestone is passed through a concentrated solution of sodium chloride (NaCl) (brine) saturated with ammonia. The reaction of CO₂ and ammonia gives ammonium bicarbonate which on reaction with sodium chloride gives sodium bicarbonate (NaHCOg). Sodium bicarbonate gets precipitated because of its low solubility in water.

i) NH₃(g) +H₂O(l) +CO₂(g) →NH₄HCO₃(aq)

ii) NH₄HCO₃(aq) +NaCl(aq) → NH₄Cl(aq) +NaHCO₃(s)

The filtrate containing ammonium chloride is reacted with lime to form ammonia which is again used to saturate brine solution (NaCl).
(b) Sodium bicarbonate is obtained as a white crystalline solid by filtration and is well washed so as to free it from ammonium compound.
(c) Sodium bicarbonate is heated to convert it into sodium carbonate.

2NaHCO₃(s)+ heat → Na₂CO₃ +H₂O(l) +CO₂(G)

Ammonium chloride and carbon dioxide are used again and again and so the manufacture of sodium carbonate involves only sodium chloride and limestone as the cheap raw materials. The overall flow chart is given below in Figure Thus only limestone and sodium chloride are consumed and washing soda can be continuously manufactured.

Some More Questions From Control and Coordination Chapter

You are given the following solutions:

Hydrochloric acid (HCl), sulphuric acid (H₂SO₄), nitric acid (HNO₃), acetic acid (CH₃COOH), sodium hydroxide (NaOH), calcium hydroxide [(Ca(OH)₂], potassium hydroxide (KOH), magnesium hydroxide [Mg(OH)₂] and ammonium hydroxide (NH₄OH). Give the colour change for each of these solutions with red litmus, blue litmus, phenolphthalein and methyl orange solutions.

Choose the olfactory indicators and give their characteristics: red cabbage extract, onion, vanilla extract, litmus, clove oil.

What do you understand by concentrated and dilute acids?

How do metals react with bases?

What is a neutralization reaction? Give some examples.

What are non-metallic oxides? Substantiate your answer.

Take 5 ml hydrochloric acid in a boiling tube or a conical flask. Add a few pieces of zinc granules to it.

(a) What do you observe on the surface of zinc granules?
(b) Name the gas evolved.
(c) What happens when the above gas is passed through soap solution?
(d) What happens when a burning candle is brought near the gas filled tube?

Name four acids and bases. Write their formulae.

Name the various kind of oxides and mention their properties.

What are acids? How are they produced?

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