CHEMISTRY IN INDUSTRY

NITROGEN CHEMISTRY

NITROGEN

• triple bond between two atoms in a diatomic molecule
• triple bond has high enthalpy meaning nitrogen is not very reactive - lots of energy required to break bond, reactions often require a catalyst

AMMONIA

• N2 + 3H2 → 2NH3
• nitrogen hydride NH3
• lone pair of electrons on nitrogen atom can form dative covalent bonds (such as with hydrogen atoms, meaning ammonia acts as a base)
• trigonal pyramidal shape

AMMONIUM IONS

• NH3 + H+ ⇌ NH4+
• ammonia's lone pair forms a dative covalent bond with a hydrogen ion
• tetrahedral shape
• tested for by gently heating a sample with sodium hydroxide, causing the evolution of ammonia gas

NITROGEN OXIDES

• NITROGEN OXIDE - colourless gas, turns to brown NO2 in air. Formed from combustion processes, thunderstorms, in soil by denitrifying bacteria. N2 + O2 → 2NO
• NITROGEN DIOXIDE - brown gas. Formed from oxidation of NO in atmosphere. 2NO + O2 → 2NO2.
• DINITROGEN OXIDE - colourless gas. Formed in soil by denitrifying bacteria.

NITRATE IONS

WHEN OXYGEN CONTENT IS LOW, ANAEROBIC BACTERIA REDUCE NITRATE (III) IONS IN SEQUENCE: NO2- → NO → N2O → N2

• very soluble in water
• made through oxidation of ammonium ions from aerobic bacteria in the soil, whereby the bacteria carry out the reactions to gain respiratory energy
• process is NITRIFICATION

NITRATE(III) IONS

• NO2-
• NH4+ + 1 1/2 O2 → NO2- + 2H+ + H2O

NITRATE(V) IONS

• NO3-
• NO2- + 1/2 O2 → NO3-
• tested for by gently heating a sample with sodium hydroxide and Devarda's alloy, causing the evolution of ammonia gas

EQUILIBRIUM

PRESSURE + THE EQUILIBRIUM CONSTANT

• increasing the…