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Home » Discuss the principle and method of softening of hard water by synthetic ionexchange resins.
Discuss the principle and method of softening of hard water by synthetic ionexchange resins.
CBSE | Chemistry | Class 11 | Exercise 1 | Hydrogen | NCERT
Discuss the principle and method of softening of hard water by synthetic ionexchange resins.

Solution:

The method involved with treating extremely durable hardness of water utilizing engineered saps commonly based or trade of anions and cations present in water by \mathrm{OH}^{-}and \mathrm{H}^{+}ions, separately.

Two kinds of manufactured pitches are

Anion trade pitches

Cation trade pitches

Cation trade pitches are enormous natural particles that contain the -\mathrm{SO}_{3} \mathrm{H} bunch. Initially the gum get changed into RNa by treating it with \mathrm{NaCl}. This pitch trades \mathrm{Na}^{+}ions with \mathrm{Ca}^{2+} particles and \mathrm{Mg}^{2+} particles, subsequently making the water delicate.

2 R N a+M_{(a q)}^{2+} \rightarrow R_{2} M_{(s)}+2 N a_{(a q)}^{+}

There are cation trade tars in \mathrm{H}^{+}form. The tars trade \mathrm{H}^{+}ions for \mathrm{Na}^{+}, \mathrm{Ca}^{2+}, and \mathrm{Mg}^{2+} particles.

2 R H+M_{(a q)}^{2+} \rightleftharpoons M R_{2(s)}+2 H_{(a q)}^{+}

Anion trade tars trade \mathrm{OH}^{-}ions for anions like \mathrm{Cl}^{-}, \mathrm{HCO}_{3}^{-}and S O_{4}^{2-} present in water.

R N H_{2(s)}+H_{2} O_{(l)} \rightleftharpoons R N H_{3}^{+} . O H_{(s)}^{-} R N H_{3}^{+} \cdot X_{(s)}^{-}+O H_{a q)}^{-}

During the entire cycle, first the water goes through the cation trade measure. The water which is gotten after this interaction is liberated from mineral cations and normally acidic. This acidic water is then gone through the anion trade measure where OH– ions neutralize the H+ ions and de-ionize the water acquired.

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