Free Nitrogen & sulfur questions for AS Level Chemistry (9701), part of Inorganic chemistry. Each question has the answer and the marking points an examiner would look for.
Generate a full Nitrogen & Sulfur worksheet →All Inorganic chemistry questionsNitrogen and its compounds are important in the atmosphere.
1 The ammonium ion is tetrahedral.
2 Nitrogen oxides are removed from car exhausts by reaction with oxygen in catalytic converters.
3 Ammonia acts as a Brønsted–Lowry acid when it reacts with HCl.
Which statements are correct?
Answer: D
Which term is described by this statement?
“Reaction of nitrogen and hydrogen to make ammonia using an iron catalyst, about 450 °C and 200 atm.”
Answer: C
In the Haber process, N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = −92 kJ mol−1. At equilibrium the partial pressures are N₂ 4.0 MPa, H₂ 9.0 MPa and NH₃ 1.2 MPa.
Write the expression for Kp and calculate its value, giving its units.
Explain why a temperature of about 450 °C is used, even though the forward reaction is exothermic.
State and explain the effect of increasing the total pressure on the yield of ammonia.
Describe a test for the ammonium ion.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 4.94 × 10−4 MPa−2 Kp = p(NH₃)2/(p(N₂) × p(H₂)3) M1 = 4.94 × 10−4 A1 MPa−2 A1 | 3 |
| (b) | compromise between rate and yield lower temperature gives a higher yield but the rate would be too slow M1 450 °C is a compromise M1 | 2 |
| (c) | increases yield yield increases M1 equilibrium shifts to the side with fewer moles of gas M1 | 2 |
| (d) | warm with NaOH(aq); gas turns damp red litmus blue warm with NaOH(aq) and the ammonia given off turns damp red litmus blue B1 | 1 |
Nitrogen and sulfur oxides are atmospheric pollutants.
Explain why nitrogen is unreactive.
Explain how oxides of nitrogen catalyse the oxidation of SO₂ in the atmosphere.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | strong triple bond; non-polar strong N≡N triple bond (high bond energy) B1 non-polar molecule B1 | 2 |
| (b) | NO₂ oxidises SO₂, NO regenerated NO₂ + SO₂ → NO + SO₃ B1 NO + ½O₂ → NO₂ (catalyst regenerated) B1 | 2 |
This question is about nitrogen and sulfur.
Explain why nitrogen gas is very unreactive.
Explain why ammonia acts as a Brønsted–Lowry base, and draw a dot-and-cross diagram of the ammonium ion.
Describe how oxides of nitrogen are formed in a car engine and removed by a catalytic converter. Include equations.
Explain the role of NO₂ as a catalyst in the oxidation of atmospheric SO₂. Include equations.
State one environmental consequence of nitrate fertiliser run-off.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | N≡N triple bond, very high bond energy; non-polar the N≡N triple bond has a very high bond energy B1 and the molecule is non-polar B1 | 2 |
| (b) | lone pair accepts H⁺; NH₄⁺ with dative bond lone pair on N accepts a proton B1 NH₄⁺ diagram with four shared pairs B1 one dative bond shown / overall + charge B1 | 3 |
| (c) | N₂ + O₂ → 2NO at high T; 2NO + 2CO → N₂ + 2CO₂ high temperature in the engine allows N₂ and O₂ to react B1 N₂ + O₂ → 2NO B1 in the catalytic converter 2CO + 2NO → 2CO₂ + N₂ B1 on a platinum / rhodium surface B1 | 4 |
| (d) | NO₂ + SO₂ → NO + SO₃; NO + ½O₂ → NO₂; regenerated SO₂ + NO₂ → SO₃ + NO B1 NO + ½O₂ → NO₂ B1 NO₂ is regenerated so acts as a catalyst B1 | 3 |
| (e) | eutrophication eutrophication / algal bloom leading to deoxygenation of water B1 | 1 |
Oxides of nitrogen and sulfur are atmospheric pollutants.
Explain how nitrogen monoxide is formed in a car engine.
NO₂ acts as a catalyst in the oxidation of SO₂ in the atmosphere. Write two equations to show this.
Write an equation for the removal of NO in a catalytic converter.
State the oxidation number of nitrogen in NO₂ and in HNO₃.
Write an equation for the formation of sulfuric acid from SO₃.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | N₂ + O₂ → 2NO at high temperature N₂ + O₂ → 2NO B1 high temperature provides energy to break the strong N≡N bond B1 | 2 |
| (b) | NO₂ + SO₂ → NO + SO₃; NO + ½O₂ → NO₂ NO₂ + SO₂ → NO + SO₃ B1 NO + ½O₂ → NO₂ B1 | 2 |
| (c) | 2CO + 2NO → 2CO₂ + N₂ 2CO + 2NO → 2CO₂ + N₂ B1 | 1 |
| (d) | +4 and +5 +4 and +5 B1 | 1 |
| (e) | SO₃ + H₂O → H₂SO₄ SO₃ + H₂O → H₂SO₄ B1 | 1 |
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