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प्रश्न
how can demineralised be obtained?
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उत्तर
Demineralised water is obtained by passing water successively through a cation exchange (in the H+ form) and an anion exchange (in the OH– form) resin.
During the cation exchange process, H+ exchanges for Na+, Mg2+, Ca2+, and other cations present in water.
\[\ce{2RH_{(s)} + M^{2+}_{(aq)} ⇌ MR_{2(s)} + 2H^+_{(aq)}}\] ....(1)
In the anion exchange process, OH– exchanges for anions such as
\[\ce{CO^{2-}_3, SO^{2-}_4, Cl^-, HCO^-_3}\] etc. present in water.
\[\ce{RNH_{2(s)} + H_2O_{(l)} <=> RNH^+_3 . OH^-_{(s)}}\]
\[\ce{RNH^+_3OH^-_{(s)} + X^-_{(aq)} ⇌ RNH^+_3 . X^-_{(s)} + OH^-_{(aq)}}\] ....(2)
OH– ions liberated in reaction (2) neutralize H+ ions liberated in reaction (1), thereby forming water.
\[\ce{H^+_{(aq)} + OH^-_{(aq)} -> H_2O_{(l)}}\]
संबंधित प्रश्न
What is meant by ‘demineralised’?
Is demineralised or distilled water useful for drinking purposes? If not, how can it be made useful?
The oxide that gives \[\ce{H2O2}\] on treatment with dilute \[\ce{H2SO4}\] is ______.
When sodium peroxide is treated with dilute sulphuric acid, we get ______.
Which of the following ions will cause hardness in water sample?
Hardness of water may be temporary or permanent. Permanent hardness is due to the presence of:
(i) Chlorides of \[\ce{Ca}\] and \[\ce{Mg}\] in water.
(ii) Sulphates of \[\ce{Ca}\] and \[\ce{Mg}\] in water.
(iii) Hydrogen carbonates of \[\ce{Ca}\] and \[\ce{Mg}\] in water.
(iv) Carbonates of alkali metals in water.
Complete the following equations:
\[\ce{PbS (s) + H2O2 (aq) ->}\]
Complete the following equations:
\[\ce{CO (g) + 2H2 (g) ->[Cobalt][Catalyst]}\]
Discuss briefly de-mineralisation of water by ion exchange resin.
Why is the Ionisation enthalpy of hydrogen higher than that of sodium?
Assertion (A): Permanent hardness of water is removed by treatment with washing soda.
Reason (R): Washing soda reacts with soluble magnesium and calcium sulphate to form insoluble carbonates.
Which one of the following methods is most suitable for preparing deionized water?
100 ml of a water sample contains 0.81 g of calcium bicarbonate and 0.73 g of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalent of CaCO3 is ______.
[Molar mass of calcium bicarbonate is 162 g mol-1 and magnesium bicarbonate is 146 g mol-1)
