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Hydrogen

Short Answer Type

131. Do you expect different products in solution when aluminium (III) chloride and potassium chloride are treated separately with:
(i) normal water (ii) acidifed water and (iii) alkaline water?

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132.

What is hard and soft water?

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Long Answer Type

133. What causes the temporary and permanent hardness of water?
Or
Distinguish clearly between temporary hardness and permanent hardness.
Or
What is hardness of water due to? What are its types?

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Short Answer Type

134.

Why does hard water not form lather with soap?

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Long Answer Type

135.

What are different methods used for softening of hard water?

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136. What is ‘demineralised water’ and how can it be obtained?

Water which does not contain cations and anions is called demineralised water. It is obtained by passing hard water first through cation exchange resin and then through anion exchange resin.

During the cation exchange process, H⁺ exchange for Na⁺, Mg²⁺, Ca²⁺ and other cations present in water.

In anion exchange process OH- exchange for anions such as Cl^-, HCO₃^- etc. present in water.

ions liberated in reaction 1 and 2 neturlaize each other, thus forming water.

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137. Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
Or
What do you mean by synthetic ion-exchange resins?

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