f.4 chemistry

All Group I oxides react with water to give soluble hydroxides.
Li2O(s) + H2O(l) → 2LiOH(aq)
Na2O(s) + H2O(l) → 2NaOH(aq)
K2O(s) + H2O(l) → 2KOH(aq)
Rb2O(s) + H2O(l) → 2RbOH(aq)
Cs2O(s) + H2O(l) → 2CsOH (aq)

For Group II oxides, BeO and MgO are insoluble in water, and all other Group II oxides react with water to give soluble hydroxides (but the solubility is low).
CaO(s) + 2H2O(l) → Ca(OH)2(aq)
SrO(s) + 2H2O(l) → Sr(OH)2(aq)
BaO(s) + 2H2O(l) → Ba(OH)2(aq)

All other metal oxides are insoluble in water.

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Equations for the reaction between dilute ammonia solution and copper(II) sulphate solution is :
2NH3(aq) + 2H2O(l) + CuSO4(aq) → (NH4)2SO4(aq) + Cu(OH)­2(s)
Note that ammonia solution contains mainly the solution NH3 molecule (and NH4OH does not exist), so write in the form 2NH3 + 2H2O instead of 2NH4OH.

The reaction can also be represented by two ionic equations :
NH3(aq) + H2O(l) = NH4+(aq) + OH-(aq) ... (reversible reaction)
Cu2+(aq) + 2OH-(aq) → Cu(OH)2