Question 26
(a) Classify following oxides as neutral, acidic, basic or amphoteric:
CO, B2O3, SiO2, CO2, Al2O3, PbO2, Tl2O3
(b) Write suitable chemical equations to show their nature.
(1) CO = Neutral
(2) B2O3 = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium metaborate.
B2O3 + 2NaOH → 2NaBO2 + H2O
(3) SiO2 = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium silicate.
SiO2 + 2NaOH → 2Na2SiO3 + H2O
(4) CO2 = Acidic
Being acidic, it reacts with bases to form salts. It reacts with NaOH to form sodium carbonate.
CO2 + 2NaOH → 2Na2CO3 + H2O
(5) Al2O3 = Amphoteric
Amphoteric substances react with both acids and bases. Al2O3 reacts with both NaOH and H2SO4.
Al2O3 + 2NaOH → NaAIO2
Al2O3 + 3H2SO4 → Al2(SO4)3 + 3H2O
(6) PbO2 = Amphoteric
Amphoteric substances react with both acids and bases. PbO2 reacts with both NaOH and H2SO4.
PbO2 + 2NaOH → Na2PbO3 + H2O
PbO2 + 2H2SO4 → 2PbSO4 + 2H2O +O2
(7) Tl2O3 = Basic
Being basic, it reacts with acids to form salts. It reacts with HCl to form thallium chloride.
Tl2O3 + 6HCl → 2TlCl3 + 3H2O
