Topic 7 - Organic Chemistry

Question 1

What is a hydrocarbon

Answer 1

A compound only containing hydrogen and carbon atoms

Question 2

What is an alkane

Answer 2

Type of hydrocarbon containing only single bonds (so its saturated)

Question 3

What is the general formula for alkanes

Answer 3

CnH2n+2

Question 4

How do hydrocarbon properties chain depending on its length

Answer 4

• The shorter the chain the more runny it is (less viscous)
• shorter chains are more volatile (have a lower boiling point)
• shorter chains are more flammable

Question 5

What is complete combustion

Answer 5

Happens when there is enough oxygen
- hydrocarbon + oxygen > carbon dioxide + water
- releases lots of oxygen

Question 6

What is crude oil

Answer 6

• A fossil fuel formed from the remains of plants and animals
• non renewable
• a mixture of hydrocarbons, most of which are alkanes

Question 7

How is crude oil seperated

Answer 7

Fractional distillation

Question 8

Describe the process of fractional distillation

Answer 8

1. The oil is heated until it has turned into gas and the gasses enter a fractioning column
2. In the column there is a temp gradient (hottest at the bottom)
3. Longer hydrocarbons have higher boiling points - they condense and drain early on
4. Crude oil separated into different fractions

Question 9

What is cracking

Answer 9

The splitting up of long chain hydrocarbons

Question 10

Describe the process of cracking

Answer 10

1. Heat long chain hydrocarbons to vaporize them
2. The vapour is passed over a hot powdered aluminium oxide (catalyst)
3. Long chain molecules split apart on the surface of the specks of the catalyst - catalytic cracking
4. You can crack hydrocarbons by mixing the vapour with steam - steam cracking

Question 11

What’s an alkene

Answer 11

Type of hydrocarbon containing a double bond making them unsaturated

Question 12

What is the general formula for an alkene

Answer 12

CnH2n

Question 13

How do alkenes react

Answer 13

Via addition reactions - the double carbon bond opens up

Question 14

What is hydrogenation

Answer 14

• Addition of a hydrogen to an alkene - double bond opens up forming an saturated alkane
• happens in the presence of a catalyst

Question 15

What is formed when you react steam with alkenes

Answer 15

Alcohols

Question 16

How is bromine used to test for alkenes

Answer 16

1. When orange bromine water is added to a saturated compound no reaction will happen
2. If it is added to an alkene it will react causing the bromine water to decolorise

Question 17

What are polymers

Answer 17

Made up of lots of the same molecules joined together e.g plastics

Question 18

What are addition polymers made from

Answer 18

Unsaturated monomers

Question 19

What are alcohols

Answer 19

• A homologous series with the functional group OH
• used as solvents and fuels
• can be made by fermentation

Question 20

What properties do alcohols have

Answer 20

• Flammable - undergo complete combustion in air
• first four are soluble in water

Question 21

What are carboxylic acids

Answer 21

• A homologous group with the functional group COOH e.g ethanoic acid
• they can dissolve in water - they ionise and release H+ ions- form weak acidic solutions

Question 22

What is produced when a carboxylic acid react with carbonates

Answer 22

• a salt, water, and carbon dioxide
• e.g ethanoic acid + sodium carbonate > sodium ethanoate + water + carbon dioxide

Question 23

What functional group do esters have

Answer 23

COO

Question 24

How are esters formed

Answer 24

Alcohol + carboxylic acid > (acid catalyst) > ester + water

Question 25

What is condensation polymerisation

Answer 25

Monomers containing different functional groups react together and bonds form. For each bind formed a small molecule is lost.

Question 26

What are some examples of naturally occurring polymers

Answer 26

Proteins, nucleotide polymers etc