Organic Chemistry

Question 1

What is crude oil formed from?

Answer 1

The fossilised remains of plankton.

Question 2

Where is crude oil found?

Answer 2

Porous rocks in the Earth’s crust.

Question 3

What is viscosity?

Answer 3

How easily a substance flows.

Question 4

What are qualities of larger hydrocarbons?

Answer 4

More viscous.
Higher boiling point.
Less volatile.
Less flammable.

Question 5

How can crude oil be separated in different fractions?

Answer 5

Fractional distillation.

Question 6

Describe the process of fractional distillation.

Answer 6

Crude oil is heated until it evaporates.
Vapour moves up fractionating column.
The top of the column is much colder than the bottom.
Shorter hydrocarbon reach the top, before they condense.
Longer hydrocarbons condense at the bottom.

Question 7

List fractions with high boiling points.

Answer 7

Bitumen (used in roads).

Fuel oil.

Question 8

List fractions that condense in the middle of the fractionating column?

Answer 8

Kerosene.

Diesel oil.

Question 9

List fractions with low boiling points.

Answer 9

Refinery gas.

Gasoline (petrol).

Question 10

What are saturated hydrocarbons?

Answer 10

Contain the maximum number of bonds possible.

Question 11

What are some qualities of alkanes?

Answer 11

Saturated hydrocarbons.
Fairly unreactive.
Flammable.

Question 12

What is the general formula for alkanes?

Answer 12

CnH*(2n+2)

Question 13

List the first ten alkanes.

Answer 13

Methane.
Ethane.
Propane.
Butane.
Pentane.
Hexane.
Heptane.
Octane.
Nonane.
Decane.

Question 14

What are properties of shorter chain alkanes?

Answer 14

They release more energy more quickly by burning, so there is a greater demand for them as fuels.

Question 15

What happens during combustion of hydrocarbon fuels?

Answer 15

Both carbon and hydrogen are oxidised.
Energy is released.
Waste products are produced, which are released into the atmosphere.

Question 16

What happens if combustion is not complete?

Answer 16

Carbon monoxide, unburnt fuels and soil particles containing soot (carbon) may be released.

Question 17

What are solid particles in the air?

Answer 17

Particulates.

Question 18

What do particulates cause?

Answer 18

Global dimming and damage to people’s lungs.

Question 19

What is global dimming?

Answer 19

When particulates reduce the amount of sunlight reaching the Earth’s surface.

Question 20

What happens with the high temperatures in burning fuels?

Answer 20

Causes nitrogen in the air to react with oxygen to form nitrogen oxides.

Question 21

What are effects of nitrogen oxides?

Answer 21

Cause respiratory problems in people and react with rain water to form acid rain, which damages plants and buildings.

Question 22

What is the process of cracking?

Answer 22

When longer chain hydrocarbons are broken down into shorter, more useful hydrocarbons.

Question 23

What are the two main methods of cracking?

Answer 23

Steam cracking.

Catalytic cracking.

Question 24

Describe the process of steam cracking.

Answer 24

Hydrocarbons are mixed with steam and heated to 850 degrees Celsius.

Question 25

Describe the process of catalytic cracking.

Answer 25

Hydrocarbons are heated until they vaporise.
Vapour is passed over a hot aluminium oxide catalyst.
A thermal decomposition reaction takes place.

Question 26

What are some products of cracking?

Answer 26

Alkanes and alkenes.

Question 27

What can alkenes be used to make?

Answer 27

New compounds, such as polymers and industrial alcohol.

Question 28

What can be used to differentiate between alkanes and alkenes?

Answer 28

As alkenes are more reactive than alkanes, if they are placed into bromine water and shaken, the bromine water will turn from orange to colourless.