Question -
Answer -
Demineralised water isfree from all soluble mineral salts which is obtained by passing watersuccessively through a cation exchange (in the form of H+) and an anion exchange in the form of OH– resins.
H+ exchanges forNa+, Ca2+,Mg2+ and other cations presentin water. This process results in release of proton which makes the wateracidic.
OH– exchanges, for anions like Cl–, HCO3–,SO42-etc.
OH– ions thus liberatedneutralize the H+ ions set freein the cation exchange process. H+(aq)+ OH–(aq) ——-> H2O(l)