Alevel Chemistry Revision IC 13
Revision Material
Duration: 2nd – 8th March
Topic 13 Nitrogen and sulfur
The topic introduces some of the chemistry associated with nitrogen and sulfur
Learning outcomes
Candidates should be able to:
11.1 Nitrogen (a) explain the lack of reactivity of nitrogen
(b) describe and explain:
(i) the basicity of ammonia (see also Section 7.2)
(ii) the structure of the ammonium ion and its formation by an acid-base reaction
(iii) the displacement of ammonia from its salts
(c) state the industrial importance of ammonia and nitrogen compounds derived from ammonia
(d) state and explain the environmental consequences of the uncontrolled use of nitrate
fertilisers
(e) state and explain the natural and man-made occurrences of oxides of nitrogen and their
catalytic removal from the exhaust gases of internal combustion engines
(f) explain why atmospheric oxides of nitrogen are pollutants, including their catalytic role in the
oxidation of atmospheric sulfur dioxide (see also Section 8.3(e)(iii))
11.2 Sulfur: the formation of (a) describe the formation of atmospheric sulfur dioxide from the combustion of sulfur-
atmospheric sulfur contaminated fossil fuels
dioxide, its role in acid (b) state the role of sulfur dioxide in the formation of acid rain and describe the main
rain environmental consequences of acid rain
, 13.1 Nitrogen
(a) Explain the lack of reactivity of nitrogen
N≡N bond is very strong (triple bond)
Large amount of energy required to break it OR Ea is very high
Why it is inert
- Triple bond
- Non-polar / no dipole
- Needs a lot of energy to break
- It reacts only under extreme temperature or pressure or in presence of catalyst
(b) Converting N2 into different forms of compounds
(i) Natural process.- lightning
Lightning provides the activation energy needed for this reaction to occur
N2(g) + O2(g) → 2NO(g)
2NO(g) + O2(g) → 2NO2(g) red brown
2NO2(g) + H2O(l) + O2(g) → 4HNO3(aq)
(ii) Bio-process -beans
(iii) Haber process
3H2(g) + N2(g) ↔ 2NH3(g)
condition: 400 – 450°, 200 atm, Fe(s)
NH3(g) + H+ → NH4+ fertilisers
(iv) Pollutants from car exhausts
N2(g) + O2(g) → 2NO(g) high temperature [car engine]. 2NO(g) + O2(g) → 2NO2(g) r.t.p
Acid rain
Nitrogen oxides released from the car exhausts will cause acid rain
The acid rain will destroy forests and kill fishes in lakes/rivers
It will also corrode building
4NO + 2H2O + 3O2 → 4HNO3(aq)
4NO2 + 2H2O + O2 → 4HNO3(aq) [large amount]
The nitrogen oxides released can also cause the releasing of NOx
4CO(g) + 2NO2(g) → (𝑝𝑡) 4CO2(g) + N2(g)
(v) Ammonia and ammonium (NH3, NH4+)
NH3(g) + H+ → NH4+
+ H+ →
pyramidal 107°, tetrahedral
basic (pH = 10 – 12) acidic (pH = 3 – 5)
Long pair of e s of nitrogen forms a coordinate bond with the H+ ion
-
How does ammonia act as a base
Ammonia is a weak base because there is a lone pair of electrons on the nitrogen atom that allow molecule to
accept a proton, forming an ammonium ions
Revision Material
Duration: 2nd – 8th March
Topic 13 Nitrogen and sulfur
The topic introduces some of the chemistry associated with nitrogen and sulfur
Learning outcomes
Candidates should be able to:
11.1 Nitrogen (a) explain the lack of reactivity of nitrogen
(b) describe and explain:
(i) the basicity of ammonia (see also Section 7.2)
(ii) the structure of the ammonium ion and its formation by an acid-base reaction
(iii) the displacement of ammonia from its salts
(c) state the industrial importance of ammonia and nitrogen compounds derived from ammonia
(d) state and explain the environmental consequences of the uncontrolled use of nitrate
fertilisers
(e) state and explain the natural and man-made occurrences of oxides of nitrogen and their
catalytic removal from the exhaust gases of internal combustion engines
(f) explain why atmospheric oxides of nitrogen are pollutants, including their catalytic role in the
oxidation of atmospheric sulfur dioxide (see also Section 8.3(e)(iii))
11.2 Sulfur: the formation of (a) describe the formation of atmospheric sulfur dioxide from the combustion of sulfur-
atmospheric sulfur contaminated fossil fuels
dioxide, its role in acid (b) state the role of sulfur dioxide in the formation of acid rain and describe the main
rain environmental consequences of acid rain
, 13.1 Nitrogen
(a) Explain the lack of reactivity of nitrogen
N≡N bond is very strong (triple bond)
Large amount of energy required to break it OR Ea is very high
Why it is inert
- Triple bond
- Non-polar / no dipole
- Needs a lot of energy to break
- It reacts only under extreme temperature or pressure or in presence of catalyst
(b) Converting N2 into different forms of compounds
(i) Natural process.- lightning
Lightning provides the activation energy needed for this reaction to occur
N2(g) + O2(g) → 2NO(g)
2NO(g) + O2(g) → 2NO2(g) red brown
2NO2(g) + H2O(l) + O2(g) → 4HNO3(aq)
(ii) Bio-process -beans
(iii) Haber process
3H2(g) + N2(g) ↔ 2NH3(g)
condition: 400 – 450°, 200 atm, Fe(s)
NH3(g) + H+ → NH4+ fertilisers
(iv) Pollutants from car exhausts
N2(g) + O2(g) → 2NO(g) high temperature [car engine]. 2NO(g) + O2(g) → 2NO2(g) r.t.p
Acid rain
Nitrogen oxides released from the car exhausts will cause acid rain
The acid rain will destroy forests and kill fishes in lakes/rivers
It will also corrode building
4NO + 2H2O + 3O2 → 4HNO3(aq)
4NO2 + 2H2O + O2 → 4HNO3(aq) [large amount]
The nitrogen oxides released can also cause the releasing of NOx
4CO(g) + 2NO2(g) → (𝑝𝑡) 4CO2(g) + N2(g)
(v) Ammonia and ammonium (NH3, NH4+)
NH3(g) + H+ → NH4+
+ H+ →
pyramidal 107°, tetrahedral
basic (pH = 10 – 12) acidic (pH = 3 – 5)
Long pair of e s of nitrogen forms a coordinate bond with the H+ ion
-
How does ammonia act as a base
Ammonia is a weak base because there is a lone pair of electrons on the nitrogen atom that allow molecule to
accept a proton, forming an ammonium ions
