Question

Metal A has an electronic configuration of 2,8,1 and metal B has 2,8,8,2 which is a more reactive metal.

(a) Identify A and B and give their reactions with dil.HCl and dil.$H_{2}S{O}_4$.

(b) Give the effect of heat on their:

(i) oxides, (ii) hydroxides,

(iii) carbonates, (iv) nitrates.

Answer 1

The metal A is more reactive than metal B.

(a) The electronic configuration of 2,8,1 -----> Atomic number is 11 -----> The metal A is Na (Sodium).

and the electronic configuration of 2,8,8,2 -----> Atomic number is 20 ----> The metal B is Ca (Calcium).

Reaction with HCl:

$2Na+2HCl\to 2NaCl+H_2$

$Ca+2HCl\to CaC{l}_2+H_2$

Reaction with H2SO4 :

$2Na+H_{2}SO4\to N{a}_{2}S{O}_4+H_2$

$Ca+H_{2}S{O}_4\to CaS{O}_4+H_2$

(b)

(i) Oxides: Sodium and calcium oxides are stable to heat.

(ii) Hydroxides: Sodium hydroxide is stable to heat whereas calcium hydroxide decomposes on heating to metal oxide and water vapour.

(iii) Carbonates: Sodium carbonate is stable to heat whereas calcium carbonates decompose on heating to form calcium oxide and carbon dioxide. (iv) Nitrates: Sodium nitrate on heating form nitrite and oxygen whereas calcium nitrate decomposes on heating to form calcium oxide, nitrogen dioxide, and oxygen.