SODIUM OXIDE (Na2O)
Preparation:
(1) When sodium nitrite is heated with sodium it forms sodium oxide and nitrogen.
2NaNO2 + 6Na → 4Na2O + N2
(2) When sodium nitride and sodium nitrate are heated we get sodium oxide and N2
3Na3N + NaNO3 → 2Na2O + 5N2
(3) Sodium oxide is obtained by heating sodium and oxygen.
4Na + O2 → 2 Na2O
Properties:
(1) It is white greyish amorphous powder
(2) Sodium oxide disproportionates at 400ºC to sodium peroxide and sodium.
2Na2O
Na2O2 + 2Na
(3) It reacts with ammonia to form sodamide and sodium hydroxide.
Na2O + NH3 → NaOH + NaNH2
(4) Na2O + H2O → 2NaOH (Violent reaction)
SODIUM PEROXIDE (Na2O2)
Preparation:
When sodium is allowed to react with oxygen it forms sodium peroxide
2Na + O2 (from air, free from CO2) 
Na2O2
Properties of Na2O2:
(1) It is a yellow powder.
(2) In cold condition it reacts with water to liberate hydrogen peroxide.
Na2O2 + 2H2O (cold) → 2NaOH + H2O2
(3) In hot condition it reacts with water to liberate oxygen.
2Na2O2 + 2H2O (Hot) → 4NaOH + O2
(4) Being a basic oxide it reacts with acids and acidic oxides to form salt
Na2 O2 + → 2NaCl + H2O2
(A) Sodium peroxide reacts with carbon monoxide to form Na2CO3
Na2O2 + CO → Na2CO3
(B) Carbon dioxide is an acidic oxide and thus reacts with Na2O2 which is basic
2Na2O2 + 2CO2 → 2 Na2 CO3 + O2
(C) It reacts with the acidic SO2 to form the salt Na2SO4
Na2O2 + SO2 → Na2 SO4
(5) Sodium peroxide oxidise the sulphur in FeS to FeSO4
FeS + 4Na2O2 + 4H2O → FeSO4 + 8 NaOH
(6) It oxidises Cr in Cr (OH)3 to sodium chromate.
2Cr (OH)3 + 3Na2O2 → 2Na2CrO4 + 2NaOH + 2H2O
(Sodium chromate)
(7) It oxidises Mn2+ to MnO42–
2Mn(OH)2 + 4Na2O2 → 2Na2MnO4 + 4NaOH
(Sodium manganate)
SODIUM HYDROXIDE (NaOH)
Preparation:
(1) Soda lime process, causticisation process or Gossage process
Na2CO3 + Ca (OH)2 
2NaOH + CaCO3
(2) Castner kellner proces – Electrolytic process
Electrolyte → Brine (NaCl Solution in water)
Anode → Graphite
Cathode → Iron rods and Mercury acts as intermediate cathode by induction.
Reactions:
NaCl → Na+ + Cl–
At anode – Cl– → Cl + e
Cl + Cl → Cl2
At cathode – Na+ + e– + Hg → Na – Hg
2Na – Hg + 2H2O → 2NaOH + H2 + 2Hg
(Sodium amalgam)
Properties of NaOH:
(1) White hygroscopic solid
(2) Sodium hydroxide decomposes on heating to form sodium, hydrogen and oxygen.
2NaOH 
2Na + H2 + O2
(3) It reacts with acids to form salt and water
(A) NaOH + HCl → NaCl + H2O
(B) 2NaOH + H2SO4 → Na2SO4 + 2H2O
(4) It reacts with acidic oxides to form salt and water.
(A) 2NaOH + CO2 → Na2 CO3 + H2O
(Sodium carbonate)
(B) 2NaOH + SO2 → Na2SO3 + H2O
(Sodium sulphates)
(C) 2NaOH + SiO2 → Na2SiO3 + H2O
(5) Metals like Zn, Al, Sn, Pb etc. displace hydrogen from sodium hydroxide. Even silicon displaces from NaOH.
(A) Zn + 2NaOH → Na2ZnO2 + H2
(Sodium zincate)
(B) 2Al + 2 NaOH + 2H2O → 2Na AlO2 + 3H2
(Sodium meta-aluminate)
(C) 2 Al + 6NaOH → 2Na3AlO3 + 3H2
(Sodium aluminate)
(D) Si + 2NaOH + H2O → Na2SiO3 + 2H2
(Sodium silicate)
(6) Non metals like P, S, Cl2, Br2 disproportionate in sodium hydroxide.
(A) 4S + 6NaOH → 2Na2S + Na2S2O3 + 3H2O
(Sodium thiosulphate)
(B) 4P + 3NaOH + 3H2O → 3NaH2PO2 + PH3
(Sodium hypophosphite)
(C) Cl2 + 2NaOH (cold and dilute) → NaCl + NaClO + H2O
(Sodium hypo chloride)
(D) 3Cl2 + 6NaOH (hot and conc.) → 5 NaCl + NaClO3 + 3H2O
(Sodium chlorate)
(7) It precipitates Fe3+, Cu2+, Cd2+ etc as metal hydroxides.
(A) FeCl3 + 3NaOH → Fe (OH)3 ↓ + 3NaCl
(Brown)
(B) CuSO4 + 2NaOH → Cu (OH)2 ↓+ Na2SO4
(Green)
(C) CdCl2 + 2NaOH → Cd (OH)2 ↓ + 2NaCl
(8) Metallic salts of Al3+ and Zn2+ are precipitated as Al(OH)3 and Zn(OH)2 but in excess of NaOH these precipitation dissolve to form aluminates and zincates respectively.
(A) AlCl3 + 3NaOH → Al(OH)3 ¯+ 3NaCl
Al (OH)3 + NaOH → NaAlO2 + 2H2O
(B) Zn SO4 + 2NaOH → Zn (OH)2 + Na2SO4
Zn(OH)2 + 2NaOH → Na2ZnO2 + H2O
(9) Sodium hydroxide on heating with silver nitrate form Ag2O
2AgNO3 + 2NaOH → 2NaNO3 + H2O + Ag2O
(10) Sodium hydroxide reacts with mercurous and mercuric nitrate to form Hg2O and HgO respectively.
Hg2(NO3)2 + 2NaOH → 2NaNO3 + H2O + Hg2O
Hg(NO3)2 + 2NaOH → 2NaNO3 + H2O + HgO
