Chemistry 0.0 / 5 ? ChemistryCrude oil, cracking and hydrocarbonsGCSEAQA Created by: ruby millardCreated on: 03-04-15 12:20 Fuels from crude oil Crude oil contains many different compounds that boil at different temperatures. These burn under differen conditiions and so crude oil needs to be separated to make useful fuels. Distillation can be used to separate mixtures of liquids. Fractional distillation works because the different fractions boil (vaporise) at different temperatures. Most of the compounds in crude oil are hydrocarbons - they only conatin hydrogen & carbon. Alkanes are saturated hydrocarbons. They contain as many hydrogen atoms as possible in their molecules. 1 of 3 Fractional distillation Crude oil is separated into fractions using fractional distillation. Each fraction contains compounds with similar boiling points. The larger the molecule, the higher the boiling point of the hydrocarbon. Fractions with lower boiling points are less viscous (sticky/thick) and burn more easily, e.g. petrol. 2 of 3 Burning fuels Burning hydrocarbons in plenty of air produces carbon dioxide and water. Burning hydrocarbons in a limited supply of air may produce carbon monoxide and solid particles. Any sulfur compounds in the fuel burn to produce sulfur dioxide. Sulfur dioxide causes acid rain. Oxides of nitrogen can be formed when fuels burn under extreme conditions. Nitrogen oxides also cause acid rain. 3 of 3
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