C7 Uses and Cracking of Crude Oil (Page 152)

Question 1

Oil provides the fuel for most modern transport, such as what?

Answer 1

Cars, trains, planes

Question 2

Diesel oil, Kerosene, Heavy fuel oil, and LPG (liquid petroleum gas) all come from what?

Answer 2

Crude Oil

Question 3

The petrochemical industry uses some of the hydrocarbons from what?

Answer 3

crude oil as a feedstock to make new compounds for use in things like polymers, solvents, lubricants and detergents.

Question 4

All the products you get from crude oil are examples of organic compounds, what is this?

Answer 4

compounds containing carbon atoms

Question 5

What is the reason you get such a large variety of products using organic compounds? (carbons containing carbon atoms)

Answer 5

because carbon atoms can bond together to form different groups called homologous series. These groups contain similar compounds with many properties in common.

Question 6

Alkanes and alkenes are both examples of what series?

Answer 6

homologous series.

Question 7

What are Short-Chain hydrocarbons?

Answer 7

they are flammable so make good fuels and are in high demand.

Question 8

Long-chain hydrocarbons form what?

Answer 8

thick gloopy liquids like tar which aren’t all that useful, so a lot of the longer alkane molecules produced from fractional distillation are turned into smaller, more useful ones by a process called cracking.

Question 9

Some of the products of cracking are useful as fuels, such as?

Answer 9

petrol for cars and paraffin for jet fuel.

Question 10

What are Alkenes?

Answer 10

As well as Alkanes, cracking also produced aother type of hydrocarbon called Alkenes.

Alkenes are a lot more reactive than alkanes. They’re used as a starting material when making lots of other compounds and can be used to make polymers.

Question 11

How is Bromine water used to test for Alkenes?

Answer 11

1. When orange Bromine water is added to an alkane, no reaction will happen and it’ll stay bright orange.
2. If it’s added to an alkene and the Bromine reacts with the alkene to make a colourless compound - so the bromine water is decolourised.

(see diagram on page 152)

Question 12

What is Cracking?

Answer 12

Cracking is a thermal decomposition reaction - breaking molecules down by heating them.

Question 13

What is the process of cracking?

Answer 13

the first step is to heat long-chain hydrocarbons to vaporise them (turn them into a gas).

Then the vapour is passed over a hot powdered aluminium oxide catalyst.

the long-chain molecules split apart on the surface of the specks of a catalyst - this is catalytic cracking.

You can also crack hydroarbons if you vaporise them, mix them with steam and then heat them to a very high temperature. This is known as steam cracking.

You need to be able to balance chemical equations for cracking. please see diagram on page 152

Question 14

Pentane, C5H12, can be cracked into ethene and one other hydrocarbon. Give the balanced symbol equation for the cracking reaction?

Answer 14

C5H12 &raquo_space;» C2H4 + C3H8 (1 mark)