Organic Chemistry Part 1 - Unit 2 Topic 5

Question 1

How are fossil fuels formed?

Answer 1

Plants + animals died millions of years ago, buried in sediment in seas/swamps. Didn’t decay. Pressure + heat on these produced coal, oil + natural gas. (Made of hydrocarbons)

Question 2

What are we using when we burn fossil fuels?

Answer 2

Sun’s energy which was stored as chemical energy millions of years ago.

Question 3

What is crude oil made of?

How is crude oil removed?

Answer 3

Mixture of hydrocarbons

Drilling

Question 4

Why can hydrocarbons be separated in crude oil?

Shorter molecules =

Answer 4

Different boiling points so separated by fractional distillation.
Lower temperature to condense at.

Question 5

What is a hydrocarbon?

Answer 5

Molecule that contains only hydrogen and carbon.

Question 6

What are fossil fuels?

Examples?

Answer 6

Formed over millions of years from dead plants + animals.

Crude oil, peat, lignite + natural gas.

Question 7

What are renewable resources?

Examples?

Answer 7

Continuously supplied by nature as they are used by consumers.
Hydroelectric, wind, waves + solar energy.

Question 8

What are non-renewable resources?

Answer 8

Fuels that are finite.

Once they are used up, they can’t be replaced.

Question 9

What is fractional distillation?

How does it work?

Answer 9

Continual process of evaporation and condensation.
Heats crude oil piped in at bottom and various fractions constantly tapped off at different levels where they condense.
Bottom is warmer than top.

Question 10

How does the petro-chemical industry work?

Answer 10

Extracts crude oil from source
Transported to refineries + fractionally distilled into separate hydrocarbons
Hydrocarbons used for fuels, manufacture of dyes, plastics, fertilisers, medicines, paints + lubricants.

Question 11

3 environmental concerns of fossil fuels?

Answer 11

Transport of crude oil can lead to spills + leaks
Drilling for oil in sea bed can lead to leaks
Air pollution caused by burning fossil fuels as CO2 produced

Question 12

What is LPG?

Answer 12

Liquid Petroleum Gas

Question 13

What element does all fossil fuels contain?

Answer 13

Carbon

Question 14

What is a homologous series?

Answer 14

Family of organic compounds

Question 15

What do members of a homologous series have in common?

Answer 15

Same general formula, similar chemical properties, gradual change in physical properties, differ by CH2 unit.

Question 16

Where are alkanes present?

What is their general formula?

Answer 16

Natural gas + petroleum

C(n)H(2n + 2)

Question 17

What are 4 members of the alkanes?
(Name, formula + state at room temp)
What are alkanes called?
What do they not have?
What does this mean?

Answer 17

Methane, CH4, gas
Ethane, C2H6, gas
Propane, C3H8, gas
Butane, C4H10, gas
Saturated hydrocarbons
Functional group
Less reactive

Question 18

What is the main use for hydrocarbons?

Answer 18

Fuels.

Question 19

What is combustion?

Answer 19

Burning of a fuel in air (oxygen)

Question 20

What are the products of combustion?
What is complete combustion?
What does incomplete combustion produce?
What flame does this gas burn with?

Answer 20

CO2 + H2O
Burning in an excess of air (all C turns to CO2)
CO + H2O
Clear blue flame

Question 21

Equation for complete combustion with a hydrocarbon?

Equation for incomplete combustion with a hydrocarbon?

Answer 21

Hydrocarbon + oxygen -> carbon dioxide + water + (energy)

Hydrocarbon + oxygen -> carbon monoxide + water

Question 22

What used to be the main gas used in the UK before natural gas was discovered?

Answer 22

Coal gas

Question 23

What energy source can be used to make plastic?

Answer 23

Crude oil

Question 24

What is bond breaking?

What is bond making?

Answer 24

Pulling atoms apart. Requires energy. Endothermic.

Making new bonds. Gives out energy. Exothermic.

Question 25

What are 2 alkenes? (Name, formula + state at room temp)

Answer 25

Ethene (C2H4) Gas

Propene (C3H6) Gas

Question 26

What is the general formula for alkenes?
What do all alkenes have?
What are they called?
What can they be used to make?

Answer 26

C(n)H(2n)
At least one double bond between 2 carbon atoms
Unsaturated hydrocarbons
Polymers

Question 27

What are unsaturated hydrocarbons? E.g.

What are saturated hydrocarbons? E.g.

Answer 27

Have a double bond. Alkanes.

Don’t have a double bond. Alkenes.

Question 28

What is the test to distinguish between an alkene and an alkane?

Answer 28

Shaking hydrocarbon in bromine water which adds across the double bond of alkene to produce a halogenalkane.
Alkane = Stays orange
Alkene = Turns colourless

Question 29

What are 2 uses of polythene?

Answer 29

Cling film + bags

Question 30

Write out structural formula of methane.

Answer 30

H
               |
H------C------H
              |
             H

Question 31

Write out structural formula of ethane.

Answer 31

H      H
          |        |
H----C----C---H
          |         |
         H       H

Question 32

Write out structural formula of propane.

Answer 32

H        H        H
        |          |          |
H---C----C-----C----H
        |          |          |
       H        H        H

Question 33

Write out structural formula of butane.

Answer 33

H H H H
| | | |
H—C—–C—-C—-C—-H
| | | |
H H H H

Question 34

Write out structural formula of ethene.

Answer 34

H                   H
 |                     |
C========C
 |                     |
H                   H

Question 35

Write out structural formula of propene.

Answer 35

H      H      H
       |        |        |
H--C---C===C
       |                 |
      H               H

Question 36

How are fuels separated by fractional distillation?

Answer 36

Separate different fuels as they have different boiling points.