Question

How would you obtain:

(a) a base from another base,

(b) an alkali from a base,

(c) salt from another salt ?

Answer 1

i) Some basic compounds such as oxides of metal when dissolved in water produce strong base. For example:
Na2O + H2O → NaOH
MgO + H2O → Mg(OH)2
ii) Metal carbonates which are bases decompose on heating to produce basic metal oxides.For example:
CaCO3 → CaO + CO2
2. Alkalies are the bases which possess OH- ion and are soluble in water.These are produced from the action of water on bases such as oxides.For example:
CaO + H2O → Ca(OH)2
3. A salt from another salt can be obtained by displacement reaction:
Al(s) + NiSO4(aq) → Al2(SO4)3(aq) + Ni(s)
CaCl2(aq) + K2CO3(aq) → CaCO3(s) + KCl(aq)