Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Unit
Organic Chemistry
785 practice questions
Topics covered
Practice questions
221–230 of 785
Question 221
2 marks · Hard
Answer and see the solution →State two changes in the physical properties of hydrocarbon fractions as the number of carbon atoms in their molecules increases.
Question 222
5 marks · Hard
Answer and see the solution →Crude oil is separated into fractions by fractional distillation. Two fractions, A and B, are collected at different heights in the fractionating column.
(a)[2 marks]Fraction A consists of large hydrocarbon molecules, while fraction B consists of small hydrocarbon molecules. State which fraction is collected higher up the column. Give a reason for your answer.
(b)[2 marks]Describe how the physical properties (boiling point and viscosity) of fraction A compare to those of fraction B.
(c)[1 mark]Suggest one use for fraction B, based on its physical properties.
Question 223
2 marks · Hard
Answer and see the solution →Explain why hydrocarbons with larger molecules are less useful as fuels than those with smaller molecules.
Question 224
1 mark · Easy
Answer and see the solution →State the name of the process used to separate crude oil into fractions based on their different boiling points.
Question 225
3 marks · Easy
Answer and see the solution →Methane is a hydrocarbon fuel. Answer the following questions about its combustion.
(a)[1 mark]Write a word equation for the complete combustion of methane.
(b)[1 mark]Give the names of the two products formed in this reaction.
(c)[1 mark]Explain why methane releases energy when it burns completely in air.
Question 226
2 marks · Easy
Answer and see the solution →Incomplete combustion of hydrocarbons can take place when there is insufficient oxygen available. Explain, using your knowledge of combustion, why incomplete combustion of hydrocarbons does not produce as much energy as complete combustion.
Question 227
3 marks · Easy
Answer and see the solution →The table below shows approximate boiling points for some fractions separated from crude oil using fractional distillation. Complete the table by filling in the missing fraction names.
Fraction Approximate Boiling Point (C) Refinery gases <40 ___ 40–180 Kerosene 180–260 ___ >350 Question 228
1 mark · Easy
Answer and see the solution →State one product, other than carbon dioxide, formed during the incomplete combustion of a hydrocarbon fuel.
Question 229
3 marks · Easy
Answer and see the solution →The diagram shows a simplified fractional distillation column for crude oil. The temperature at three different positions is marked.
Fractionating column (simplified, labelled) The temperature at the bottom is 370 C, in the middle is 220 C, and at the top is 40 C.
(a)[1 mark]State what happens to the hydrocarbons as their vapours rise up the column.
(b)[1 mark]Name the fraction collected at the top of the column.
(c)[1 mark]Explain why some hydrocarbons are collected at the bottom instead of higher up.
Question 230
2 marks · Easy
Answer and see the solution →Crude oil is separated in a fractionating column. A crude oil sample produces 100 kg of gasoline, 60 kg of kerosene, and 30 kg of diesel oil after fractional distillation. The total mass of these fractions is collected.
Calculate the percentage by mass of the gasoline fraction in the sample. Give your answer to 1 decimal place.