This question is about the fractions obtained from crude oil - AQA - GCSE Chemistry - Question 4 - 2022 - Paper 2
Question 4
This question is about the fractions obtained from crude oil.
Crude oil is separated into fractions by fractional distillation.
The fractions obtained from crude oi... show full transcript
Worked Solution & Example Answer:This question is about the fractions obtained from crude oil - AQA - GCSE Chemistry - Question 4 - 2022 - Paper 2
Step 1
Explain how these fractions are obtained from crude oil by fractional distillation.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Crude oil is heated to vaporize the hydrocarbons. There is a temperature gradient in the fractional column, which is cooler at the top. Gases then condense at different levels in the column depending on their boiling points, allowing fractions to be separated. For instance, lubricating oil condenses at a higher temperature than naphtha and petroleum gases, which do not condense at all due to their lower boiling points.
Step 2
Which two are useful materials produced from this feedstock?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The useful materials produced from this feedstock are Detergents and Solvents.
Step 3
Complete the equation for the complete combustion of C₈H₂₀.
96%
101 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
C₈H₂₀ + 14 O₂ → 8 CO₂ + 10 H₂O
Step 4
Explain why sulfur impurities are removed before petrol is burned in car engines.
98%
120 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
Sulfur impurities produce sulfur dioxide when burned, which can cause acid rain and respiratory problems.
Step 5
Justify the student’s prediction.
97%
117 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
As molecular size increases, viscosity increases. Heavy fuel oil has larger molecules than kerosene, which contributes to its higher viscosity.
Step 6
Name the process which produces smaller hydrocarbon molecules from heavy fuel oil.
97%
121 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The process is called cracking.
Step 7
Give the conditions used in this process.
96%
114 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
Answer
The conditions include high temperature, typically in the range of 300°C to 900°C, and the use of steam or a catalyst.
Step 8
Which pair of hydrocarbon molecules would both turn bromine water colourless?
99%
104 rated
Only available for registered users.
Sign up now to view full answer, or log in if you already have an account!
