- Ammonia is formed between nitrogen and hydrogen, with each N atom forming covalent bonds by sharing one of its electrons to each H atom- this leaves a lone pair of electrons on the N.
- Ammonia can form hydrogen bonds with water- this makes it very soluble in water.
- The lone pair on the N atom means ammonia can form dative covalent bonds- can act as a ligand to form complex ions with transition metals.
- Ammonia can behave as a base too because of the lone pair- molecule forms a dative covalent bond with protons to form the ammonium ion (NH4+)
- Nitrogen can also form several oxides- NO is nitrogen monoxide, nitric oxide or nitrogen (ll) oxide- it is a colourless gas.
- N2O is dinitrogen monoxide, nitrous oxide or nitrogen (l) oxide- it has a sweet smell and is also a colourless gas.
- NO2 is called nitrogen dioxide or nitrogen (V) oxide- it is a brown gas which has a sharp odour and is toxic.
Nitrogen oxidation states
Form Formula Oxidation state What produces this form of N2
Nitrogen from the air N2(g) 0 Denitrifying bacteria
Ammonium ions in soil NH4+(aq) -3 Bacteria/microorganisms in soil
Nitrate(V) ions in soil NO3-(aq) +5 Nitrifying bacteria in soil/root nodules
Nitrate(lll) ions in soil NO2-(aq) +3 Nitrifying bacteria in soil/root nodules
Nitrogen(ll) oxide NO(g) +2 Thunderstorms, car engines, denitrifying bacteria
Nitrogen(V) oxide NO2(g) +4 Oxidation of NO in atmosphere
Nitrogen(l) oxide N2O(g) +1 Denitrifying bacteria in soil
The Nitrogen cycle
The Nitrogen cycle cont.
Reduction/Oxidation in the cycle:
1) N2 + 3H2 --> 2NH3
2) NH3 + H+ --> NH4+
3) NH4+ + O2 --> NO2- + 4H+ + 2e-
4) NO2- + H2O --> NO3- + 2H+ + 2e-
5) 2NO3- + 10e- + 12H+ --> N2 + 6H2O
6) N2 + O2 --> 2NO
Chemical production- cost and factors
% Atom economy = mass of desired product / total mass of all products x 100
% yield = actual product yield / theoretical yeild x 100
COSTS INVOLVED IN CHEMICAL PRODUCTION
- Raw materials
- Overheads/Fixed costs
- Disposal costs
- Some chemicals are highly flammable so carry the risk of explosions- must be stored and handled correctly.
- Some chemicals are toxic to humans- must be stored and handled correctly.
- Some chemicals can damage the environment.
Chemicals & food production
The chemical industry can help with food production-
1) Fertilising the soil- this provides the crops with nutrients which improves plant growth and crop yield.
However, rain can wash them into rivers which can cause excessive algae growth which can deplete the water of oxygen, killing off some species.
2) Acid neutralisation- adding chemicals into the soil can neutralise pH of the soil, leading to better plant growth overall.
3) Killing pests- pesticides can kill insects, weeds or moulds which all decrease crop yield and quality, so with them killed, yield and quality increases.
However, they can kill some beneficial organisms, and can be washed into water supplies which may be used for drinking water.