Chemistry C7

Question 1

Hydrocarbon definition

Answer 1

A compound made up of hydrogen and carbon only

Question 2

Types of hydrocarbons ?

Alkanes?

Answer 2

Alkanes- single bonds only (CnH2n+2)
1 carbon= methane (CH4)
2 carbons= ethane (C2H6)
3 carbons= propane (C3H8)
4 carbons= butane (C4H10)

Question 3

Crude oil definition?
How?
equipment?

Answer 3

A mixture of different length hydrocarbons
To separate crude oil we use fractional distillation
Heated through condensing column

Question 4

Where in the condensing column is it hotter?
Where is it more flammable?
Where are the hydrocarbons longer?
Where is it more viscous?

Answer 4

Hotter=bottom
Flammable=top
longer=bottom
viscous=bottom
(viscous means thickness)

Question 5

Condensing column order name/temp?
(top to bottom)
used for?

Answer 5

Gas=20°C-gas
Petrol=70°C-cars
Kerosene=170°C-planes
Diesel=270°C-trucks
Heavy fuel oil-ships
Bitumen=340°C-roads

Question 6

Test for alkenes

Answer 6

Use bromine water

If an alkene is present the water will turn orange to colourless

Question 7

What is crude oil?

Answer 7

A mixture of hydrocarbons

Question 8

What is crude oil formed from?

Answer 8

The remains of ancient biomass (mostly plankton) that was buried in mud

Question 9

What is a finite resource?

Answer 9

One that will run out

Question 10

Why is crude oil a finite resource?

Answer 10

Because it takes longer to form than the rate at which we are using it up

Question 11

What is a hydrocarbon?

Answer 11

A compound made of only carbon and hydrogen

Question 12

What is a general formula?

Answer 12

A mathematical formula which allows you to work out the chemical formula of a substance

Question 13

What is an alkane?

Answer 13

A saturated (only carbon carbon single bonds) hydrocarbon

Question 14

Name the first four alkanes

Answer 14

Methane, ethane, propane, butane

Question 15

What is the general formula for alkanes?

Answer 15

CnH2n+2

Question 16

How does boiling point change with the length of an alkane?

Answer 16

The longer the alkane, the higher its boiling point

Question 17

How does viscosity change with the length of an alkane?

Answer 17

The longer the alkane, the more viscous (less runny) it is

Question 18

How does flammability change with the length of an alkane?

Answer 18

The longer the alkane, the less flammable it is

Question 19

What is fractional distillation?

Answer 19

A process used to separate mixtures of substances with different boiling points

Question 20

What are the steps involved in fractional distillation?

Answer 20

Crude oil is vaporised, different molecules rise up the fractionating column and cool down. They condense at different points on the column.

Question 21

Which molecules are collected at the top of the column and why?

Answer 21

Small molecules as they have the lowest boiling point.

Question 22

Why is fractional distillation important?

Answer 22

Because the different fractions of crude oil have different uses

Question 23

What is a fuel?

Answer 23

A substance which when reacted with oxygen releases energy

Question 24

Name five fuels we obtain from crude oil

Answer 24

Petrol, diesel, kerosene, heavy fuel oil and liquefied petroleum gases

Question 25

What other uses are there for products of fractional distillation?

Answer 25

Solvents, lubricants, polymers and detergents

Question 26

What is combustion?

Answer 26

The reaction of a fuel with oxygen

Question 27

What are the products of complete combustion?

Answer 27

Carbon dioxide and water

Question 28

When does incomplete combustion occur?

Answer 28

When there is not enough oxygen present

Question 29

What is cracking?

Answer 29

The process of breaking down a long alkane into a shorter alkane and some alkenes

Question 30

Why is cracking important?

Answer 30

Because smaller hydrocarbons are more useful than longer ones

Question 31

What are the two types of cracking?

Answer 31

Catalytic and steam cracking