As fuels

2 marks · Easy

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.

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Show answer

55.6% (±0.1)

Also accept: 55.556%

Common mistakes: taking percentage of total crude oil rather than combined fractions

Show mark scheme and worked solution

Marking points

M1 · 1 mark · Correct method to find total mass of fractions and set up percentage calculation.

A1 · 1 mark · Correct final answer to 1 decimal place.

Worked solution

Calculate total mass of collected fractions:

Calculate percentage by mass of gasoline:

However, the question asks for percentage of gasoline in the sample (assuming total sample is the sum of these fractions):

Final answer: 55.6%