Notes on crude oil and its by-products.

Authors Avatar by kartikayguptalivecouk (student)

Crude Oil

5.6 Recall that crude oil is a mixture of hydrocarbons


5.7 Describe how the industrial process of fractional distillation separates crude oil into fractions

Crude oil is heated, vaporised, and pumped into a fractionating column, which is coolest at the top and hottest at the bottom. The larger hydrocarbons sink whilst the smaller hydrocarbons rise up the column. As they near the area where the temperature is close to their boiling point, they condense, and the fractions are collected. The refinery gases rise straight up and are collected as gases. The longer the chain of hydrocarbons, the higher its boiling point, thus the further down the fractionating column it will be.

5.8 Recall the names and uses of the main fractions obtained from crude oil: refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen

5.9 Describe the trend in boiling point and viscosity of the main fractions

As the size of the hydrocarbon molecules increases, the boiling point and viscosity increases. This is because with increasing chain length, there are more bonds that need to be broken to change state.

5.10 Recall that incomplete combustion of fuels may produce carbon monoxide and explain that carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen

Incomplete combustion of hydrocarbons produces carbon monoxide, water and soot.

Carbon monoxide is a poisonous gas. It combines with haemoglobin in the red blood cells and prevents it from carrying oxygen, hence reducing the capacity of the blood to carry oxygen

5.11 Recall that, in car engines, the temperature reached is high enough to allow nitrogen and oxygen from air to react, forming nitrogen oxides

Join now!

N2(g) + O2(g)  2NO(g)

Nitrogen oxide is a major pollutant and greenhouse gas

5.12b Recall that sulphur dioxide and nitrogen oxides are pollutant gases which contribute to acid rain, and describe the problems caused by acid rain.

Acid rain is formed when acidic air pollutants such as sulphur dioxide and nitrogen dioxide dissolve in rainwater. The sulphur dioxide and nitrogen oxides mainly come from power stations and factories burning fossil fuels, or from motor vehicles. The acid rain produces many problems. Acid rain can reduce the pH of natural water bodies from between 6.5 and 8.5 to below 4, which will ...

This is a preview of the whole essay