Answer to Question #153339 in Inorganic Chemistry for qasre

Question

Briefly explain how the following s-block compounds can be prepared

(i) 𝑀𝑔𝑂(𝑠)

(ii) 𝑁𝑎𝐶𝑙(𝑠)

Answer 1

(i) MgO can be produced by burning magnesium metal in oxygen.

2Mg + O₂ $\to$ 2MgO

However, this is rather expensive and dangerous.

Large amounts of MgO are obtained fro sea water (Magnesium chloride) by treating it with lime water to precipitate magnesium ions as Mg(OH)₂;

Mg²⁺ + Ca(OH)₂ $\to$ Mg(OH)₂ + Ca²⁺

Magnesium oxide is then roasted (Calcination) at varying temperatures to produce MgO;

Mg(OH)₂ $\to$ MgO + H₂O

(ii) NaCl can also be produced by reacting the elements sodium and chlorine;

2Na + Cl₂ $\to$ 2NaCl

However, the reaction is also expensive and dangerous. Otherwise, mass production of NaCl is by evaporation of sea water to saturation and crystallization of the solid crystals.