4.2 Crude OilEdexcel IGCSE Chemistry: Flashcards

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What is crude oil?

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What is crude oil?: A naturally occurring mixture of hydrocarbons, mostly alkanes.
What process separates crude oil into fractions, and what property does it rely on?: Fractional distillation, which relies on differences in boiling point.
Name the six main fractions of crude oil, from shortest to longest chain.: Refinery gases, gasoline, kerosene, diesel, fuel oil, bitumen.
What happens to colour, boiling point and viscosity as fraction chain length increases?: Colour darkens, boiling point increases, viscosity increases.
What is a fuel?: A substance that releases heat energy when burned.
What are the products of complete combustion of a hydrocarbon?: Carbon dioxide and water.
What can incomplete combustion produce instead of carbon dioxide?: Carbon monoxide and/or carbon (soot), as well as water.
Why is carbon monoxide poisonous?: It binds to haemoglobin in red blood cells more strongly than oxygen, reducing the blood's oxygen-carrying capacity.
How are oxides of nitrogen formed in a car engine?: The high temperature of combustion allows nitrogen and oxygen from the air to react together.
How does sulfur dioxide form from hydrocarbon fuels?: Sulfur impurities in the fuel react with oxygen during combustion.
What environmental problem do sulfur dioxide and oxides of nitrogen cause?: Acid rain.
What is cracking?: The process of breaking long-chain hydrocarbons into shorter-chain alkanes and alkenes using a hot catalyst.
What catalyst and conditions are used for cracking?: Silica or alumina catalyst, at 600-700°C.
Why is cracking necessary?: To match the oversupply of long-chain fractions to demand for shorter-chain fractions, and to produce alkenes for making plastics.
Complete: long-chain alkane → shorter-chain alkane + ___: Alkene.