Specification Point 4.14:
Know that, in car engines, the temperature reached is high enough to allow Nitrogen and Oxygen from air to react, forming Oxides of Nitrogen

Formation of Oxides of Nitrogen in Car Engines

Formation of oxides of nitrogen in car engines:

When fuels are burned in car engines, high temperatures are reached which allows Nitrogen and Oxygen from the air to combine to produce Nitrogen monoxide:

Nitrogen Monoxide formation, Edexcel IGCSE Chemistry

Nitrogen   +   Oxygen   →   Nitrogen Monoxide

N2 (g) + O2 (g) → 2NO (g)

When this Nitrogen monoxide is released from the engines of vehicles, it combines with Oxygen in the air to form Nitrogen dioxide:

Nitrogen Dioxide formation, Edexcel IGCSE Chemistry

Nitrogen Monoxide   +   Oxygen   →   Nitrogen Dioxide

2NO (g) + O2 (g) → 2NO2 (g)

Both Nitrogen monoxide and Nitrogen dioxide are produced in car engines as a result and is referred to as NOx

Specification Point 4.15:
Explain how the combustion of some impurities in Hydrocarbon fuels results in the formation of Sulfur dioxide

Combustion of Hydrocarbon Fuels

Hydrocarbon fuels: Impure Hydrocarbon fuels contain Sulfur compounds

Combustion of Hydrocarbon fuels:

During the combustion of Hydrocarbon fuels, impurities such as Sulfur compounds will be oxidised to produce sulfur dioxide:

Sulfur   +   Oxygen      Sulfur Dioxide

S (g) + O2 (g) SO2 (g)

Specification Point 4.16:
Understand how Sulfur dioxide and Oxides of Nitrogen oxides contribute to acid rain

Acid Rain

Acid rain: Rain that contains dissolved acidic gases such as sulfur dioxide and oxides of nitrogen. The pH value of normal rain is slightly below 7. The pH value of acid rain is approximately 3.4.

Contribution of sulfur dioxide and oxides of nitrogen oxide to acid rain:

Sulfur dioxide will react with oxygen and dissolve in water droplets in clouds, forming dilute sulfuric acid which will cause acid rain:

Acid rain formation, Edexcel IGCSE Chemistry

Sulfur Dioxide   +   Oxygen   +   Water   →   Sulfuric Acid

2SO2 (g) + O2 (g) + H2O (l) → 2H2SO4 (aq)

Nitrogen oxides will dissolve in water droplets in clouds, forming dilute Nitric acid and Nitrous acid, causing acid rain:

Nitrogen oxides Acid rain Edexcel IGCSE Chemistry

Nitrogen Dioxide   +   Water   →   Nitric Acid

NO2 (g) + H2O (l) → HNO3 (aq)

Acid rain, Edexcel IGCSE Chemistry

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Author: Jamie

Jamie got a First class degree in Chemistry from Oxford University before going on to teach chemistry full time as a professional tutor. He’s put together these handy revision notes to match the Edexcel IGCSE Chemistry specification so you can learn exactly what you need to know for your exams.