Asked by vk1994 | 12th Sep, 2010, 07:41: AM

Expert Answer:

Cation exchange resins contain large organic molecule with - SO3H group and are water insoluble. Ion exchange resin (RSO3H) is changed to RNa by treating it with NaCl. The resin exchanges Na+ ions with Ca2+ and Mg2+ ions present in hard water to make the water soft. Here R is resin anion.
2RNa( s )+ M 2+ (aq) → R2M(s) + 2Na+(aq)
The resin can be regenerated by adding aqueous NaCl solution.
Pure de-mineralised (de-ionized) water free from all soluble mineral salts is obtained by
passing water successively through a cation exchange (in the H+ form) and an anionexchange (in the OH form) resins.
2RH(s) + M 2+(aq) → MR2(s) + 2H+(aq)
In this cation exchange process, H+ exchanges for Na+, Ca2+, Mg2+ and other cations present in water. This process results in proton release and thus makes the water acidic. In the anion exchange process:
In this case 1% H2O2 is formed. It is extracted with water and concentrated to ~30%
(by mass) by distillation under reduced pressure. It can be further concentrated to
~85% by careful distillation under low pressure. The remaining water can be frozen
out to obtain pure H2O2.

Answered by  | 13th Sep, 2010, 09:18: AM

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