Hydrocarbons: Fuel & Feedstock Practice Questions

Crude oil is the remains of an ancient biomass that was buried in mud.

Which organisms formed most of this ancient biomass?

Tick one box.

• Coral
• Fish
• Plankton
• Trees

Crude oil is a finite resource.

What is meant by a finite resource?

Most of the compounds in crude oil are hydrocarbons.

What is a hydrocarbon?

The displayed structural formula of an alkane is shown below.

Name this alkane.

Decane is an alkane with ten carbon atoms in each molecule.

Give the molecular formula of decane.

A student says that a molecule with the formula $\mathrm{C_6H_{12}}$ is an alkane.

The student is wrong.

Explain why.

Name the process used to separate crude oil into fractions.

Give two examples of useful materials, other than fuels, that are made by the petrochemical industry from crude oil.

Before it enters the column, the crude oil is heated so that it evaporates.

Explain how the mixture of hydrocarbon vapours is then separated into fractions in the column.

Bitumen does not rise up the column and is removed as a liquid at the bottom.

Explain why.

Describe the relationship between the number of carbon atoms in a hydrocarbon molecule and its boiling point.

Use Table 1.

Petrol is used as a fuel in car engines. Heavy fuel oil is used as a fuel in large ships' engines.

Compare the viscosity and the flammability of petrol with those of heavy fuel oil.

A hydrocarbon in crude oil has a boiling point of 260 °C.

Give the fraction that this hydrocarbon will be part of.

Use Table 1.

Write a balanced symbol equation for the complete combustion of butane.

Complete the sentence.

During the complete combustion of butane, the carbon and the hydrogen in the fuel are ............................. .

A student weighed a butane cylinder before and after using the stove and found that 12.0 g of butane had been burned.

The total mass of carbon dioxide and water produced was greater than 12.0 g.

Explain why.

In catalytic cracking, the long-chain hydrocarbons are first heated so that they vaporise.

Describe what happens to the vapour next in catalytic cracking.

Describe the conditions used in steam cracking.

Balance the equation for the cracking of $\mathrm{C_{14}H_{30}}$.

$\mathrm{C_{14}H_{30} \rightarrow \rule{1cm}{0.15mm}\,C_2H_4 + C_8H_{18}}$

Explain why oil companies crack some of the fractions obtained from crude oil.

Use Table 1 and your knowledge of cracking and of the properties of hydrocarbons.

The student shook a sample of the gas collected with bromine water.

Give the colour change that the student would see, and state what this shows about the gas.

At the end of the experiment, the student must lift the delivery tube out of the water before removing the Bunsen burner.

Suggest why.

One of the alkanes in the liquid paraffin is $\mathrm{C_{15}H_{32}}$.

When this alkane is cracked it produces one molecule of $\mathrm{C_{10}H_{22}}$ and one other molecule.

Determine the formula of the other molecule.