Question

State as to why:
(a) a solution of $N{a}_{2}C{O}_3$ is alkaline ?
(b) alkali metals are prepared by electrolysis of their fused chlorides ?
(c) sodium is found to be more useful than potassium ?

Answer 1

(a) Hydrolysis of sodium carbonate in aqueous solution gives hydroxide ions. Hence, the solution is alkaline.
$C{O}_3^{2-}+H_{2}O\to HC{O}_3^{-}+O{H}^{-}$
(b) During electrolysis of aqueous solution of alkali metal chlorides, hydrogen (having lower discharge potential) is preferentially evolved than alkali metal at cathode. Hence, Electrolysis of fused alkali metal chlorides is carried out to prepare alkali metals.
(c) Sodium ions are present in blood plasma and interstitital fluids which surround the cell. Potassium ions are present in intracellular fluids. Sodium ions help in transmission of nerve signals, regulate water flow across cell membranes. Hence, sodium is more useful than potassium.