General characteristics of the compounds of alkali metals.
Answers
Basic Strength
The basic strength of these hydroxides increases as we move down the group Li to Cs.
The hydroxides of alkali metals behave as strong bases due to their low ionization energies which decrease down the group.
The decrease in ionization energies leads to weakening of the bond between metal and hydroxide ion and M – O bond in M – O – H can easily break giving M+ and OH- .
This results in the increased concentration of hydroxyl ions in the solution i.e increased basic characters.
Solubility and Stability
All these hydroxides are highly soluble in water and thermally stable except lithium hydroxide.
2LiOH +Δ → Li2O + H2O
Formation of Salts with Acids
Alkali metals hydroxides being strongly basic react with all acids forming salts.
NaOH + HCI → NaCI + H2O
2NaOH + H2SO4 → Na2SO4 + 2H2O