Salt Preparation by Direct Synthesis or Combination

When a metal burn in a gas jar containing a non metal, the two directly combine to form a salt.

Examples of direct synthesis include:

2Na_(s) + Cl_2(g) → 2NaCl_(s)
2K_(s) + Cl_2(g) → 2KCl_(s)
Mg_(s) + Cl_2(g) → MgCl_{2 (s)}
Ca_(s) + Cl_2(g) → CaCl_{2 (s)}

Some salts once formed undergo sublimation and hydrolysis.
Care should be taken to avoid water/moisture into the reaction flask during their preparation.

Heated aluminium foil reacts with chlorine to form aluminium(III)chloride that sublimes away from the source of heating then deposited as solid again.

2Al_(s) + 3Cl_2(g) → 2AlCl₃ (s/g)

Once formed aluminium(III)chloride hydrolyses/reacts with water vapour / moisture present to form aluminium hydroxide solution and highly acidic fumes of hydrogen chloride gas.

AlCl_3(s)+ 3H₂O_(g) → Al(OH)_{3 (aq)} + 3HCl_(g)

Heated iron filings reacts with chlorine to form iron(III)chloride that sublimes away from the source of heating then deposited as solid again.

2Fe_(s) + 3Cl_2(g) → 2FeCl₃ (s/g)

Once formed , aluminium(III)chloride hydrolyses/reacts with water vapour / moisture present to form aluminium hydroxide solution and highly acidic fumes of hydrogen chloride gas.

FeCl_3(s)+ 3H₂O_(g) → Fe(OH)_{3 (aq)} + 3HCl_(g)