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Crude oil is a mixture of hydrocarbons - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2023 - Paper 2
Question 6
Crude oil is a mixture of hydrocarbons. Crude oil can be separated into useful fractions by the process of fractional distillation in a fractionating column. Figure... show full transcript
Worked Solution & Example Answer:Crude oil is a mixture of hydrocarbons - Edexcel - GCSE Chemistry Combined Science - Question 6 - 2023 - Paper 2
Step 1
Step 2
Explain the trend in the viscosity of the fractions.
Answer
The viscosity of the fractions increases with the decrease in volatility. In fractional distillation, lighter fractions like gases and petrol rise to the top of the column due to their lower boiling points, while heavier fractions like bitumen remain at the bottom.
As hydrocarbon chain length increases, the intermolecular forces between molecules also increase, leading to higher viscosity. Thus, the trend shows that gases have the lowest viscosity, followed by petrol, kerosene, diesel oil, fuel oil, and finally bitumen, which has the highest viscosity.