Nitrogen & Sulfur (CIE AS Chemistry)

Nitrogen and oxygen will react together under conditions of high temperature to give oxides of nitrogen.

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N₂O₅ is a rare and unstable oxide of nitrogen.

State the systematic name of N₂O₅.

Nitrogen oxides in the atmosphere are homogeneous catalysts in the formation of acid rain.

What is meant by the following terms?

catalyst ......................................................................................

homogeneous ..........................................................................

State a major source of nitrogen oxides in the atmosphere, explaining how they are formed.

Use equations to describe the chemical role played by nitrogen oxides in the formation of acid rain.

Use the following axes in Fig. 1.1 to draw a fully labelled reaction pathway diagram showing the effect of a catalyst on an exothermic reaction.

Label the ∆H and E_a values.

Fig. 1.1

Ammonia, NH₃, is a colourless, pungent-smelling gas that has been known to man from the beginning of recorded time. Now ammonia is synthesised from its elements in the Haber process. 

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Ammonia can act as a Brønsted–Lowry base.

Explain why.

1.50 dm³ of ammonia gas were dissolved in water to form 300 cm³ of aqueous alkali at room temperature and pressure.

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Ammonia gas can also be prepared by heating a mixture of ammonium chloride and calcium hydroxide.

Give the equation for this reaction.

The high temperatures reached in an internal combustion engine cause nitrogen and oxygen from the air to react. Nitrogen monoxide is formed.

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Nitrogen oxides play a role in the formation of photochemical smog. Explain how.

The brown haze associated with photochemical smog is typically worse in cities in the afternoons of hot sunny days.

Suggest why.

Catalytic converters are fitted to exhaust systems to reduce the pollutants emitted by car engines. Nitrogen oxide, NO, and carbon monoxide, CO are removed in a catalytic converter, forming nitrogen and carbon dioxide, which are less harmful to human health.

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The combustion of fuels in motor vehicles, trains, aeroplanes and power stations produces the pollutant gas NO₂.

Write an equation to show how NO₂ is formed in these situations.

Suggest whether the production of the pollutant NO₂ would be reduced if fossil fuels were replaced by hydrogen as a fuel for combustion. Explain your answer.

In the atmosphere, NO₂ acts as a catalyst for the oxidation of SO₂ to SO₃.

SO₂ (g) + 1⁄2 O₂ (g) SO₃ (g)

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reaction 1           NO₂ (g) + SO₂ (g)  NO (g) + SO₃ (g)       ΔH = –168 kJ mol^–1

This question is about ammonia.

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Explain why the reaction between ammonium chloride and calcium hydroxide is an example of an acid-base reaction.

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A molecule of nitrogen will only react with oxygen under extreme conditions due to the strong triple bond between nitrogen atoms.

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Despite the unreactivity of nitrogen, certain extreme conditions can trigger a series of reactions from which the nitrogen in the atmosphere is involved in the production of nitric acid, causing acid rain.

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A car travelled one kilometre and released 0.23 g of an oxide of nitrogen, N_xO_y, which occupies 120 cm³.

Calculate the values of x and y.
(Assume 1 mol of gas molecules occupies 24.0 dm³).