Reaction of Period 3 Oxides with Water, Acids and Bases

Let's consider the reactions of Period 3 oxides with water, acids and bases.

1. Period 3 Oxides Reaction with Water

230703 period 3 oxide reaction with water

Sodium oxide is basic and reacts vigorously with water to form strong base sodium hydroxide, pH = 13.

Na2O + H2O → 2NaOH

Magnesium oxide is basic and reacts slowly with water to form weak base magnesium hydroxide, pH = 9 or 10.

MgO + H2 Mg(OH)2

Aluminium oxide is amphoteric but insoluble in water hence pH = 7.

Silicon dioxide is acidic but insoluble in water hence pH = 7.

P4O10 is acidic and reacts with water to form strong acid H3PO4, pH = 1 or 2.

P4O10 + 6H2 4H3PO4

SO3 is acidic and reacts with water to form strong acid H2SO4, pH = 1 or 2.

SO3 + H2 H2SO4

2. Period 3 Oxides Reaction with Acids and Bases

230703 period 3 oxide reaction with acid and base

a. Reaction with H+

All metal oxides are basic and can react with acids to form salt and water.

Na2O + 2H+  2Na+ + H2O
MgO + 2H+  Mg2+ + H2O

Aluminium oxide is amphoteric hence reacts with H+ to form salt and water.

Al2O3 + 6H+  2Al3+ + 3H2O

All non-metal oxides are acidic hence no reaction with acids.

b. Reaction with OH-

Sodium oxide and magnesium oxide are bases hence no reaction with bases.

Aluminium oxide is amphoteric hence reacts with OH- to form complex [Al(OH)4]-.

Al2O3 + 2OH- + 3H2 2[Al(OH)4]-

SiO2 is acidic and reacts with hot concentrated hydroxides to form salt and water.

SiO2 + 2OH- = SiO32- + H2O

P4O10 and SO3 are acidic hence reacts with hydroxides to form salt and water.

P4O10 + 12OH-  4PO43- + 6H2O
SO3 + 2OH-  SO42- + H2O

Topic: Periodicity, Inorganic Chemistry, A Level Chemistry, Singapore

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