C9

Question 1

crude oil

Answer 1

finite
found in rocks
formed over millions of years from the remains of tiny, ancient se animals and plants- maily plankton- that were buried in mud.
mostly hydrocarbons
mixture of different compounds that boil at different temperatures- mixture seperated to make useful fuels

Question 2

distillation

Answer 2

can separate a mixture of liquids
simple distillation of crude oil can produce liquids that boil at different temperatures- these liquid mixtures are called fractions.

Question 3

hydrocarbons

Answer 3

contain only hydrogen and carbon.
mostly alkanes(saturated hydrocarbons)

Question 4

alkanes

Answer 4

general formula CnH(2n+n)
saturated hydrocarbons
all c-c bonds single covalent bonds, no more H atoms can be added

Question 5

molecular formula

Answer 5

eg. C2H6

Question 6

fractional distillation of crude oil

Answer 6

1. crude oil is vapourised and fed into a fractionating column
2. inside the column there are many trays with holes to allow gases through. Vapours move through column getting cooler as they go up. Hydrocarbons condense to liquids when they reach the level that is their boiling point. Different liquids collect on the trays at different levels and there are outlets to collect the fractions.
3. Hydrocarbons with the smallest molecules have the lowest boiling points- these gases are collected at the top of the column. Fractions collected at bottom of column contain hydrocarbons with the highest boiling points(these are solids at room temperature)
   The fractions can be processed to produce fuels and feedstock for
   the petrochemical industry.
   Many useful materials on which modern life depends are produced
   by the petrochemical industry, such as solvents, lubricants,
   polymers, detergents.

Question 7

fractionating column

Answer 7

tall tower that is hot at the bottom and cooler going up the column

Question 8

small hydrocarbon molecules

Answer 8

lower boiling points
lower viscosities- are runny liquids
very flammable-ignite easily
burn with clean flames, producing little smoke- useful as fuels

Question 9

fractional distillation is possible because…

Answer 9

the boiling point of a hydrocarbon depends on the size of its molecule - larger molecule = higher boiling point.

Question 10

why are there so many carbon compounds

Answer 10

The vast array of natural and synthetic carbon compounds occur
due to the ability of carbon atoms to form families of similar
compounds.

Question 11

burning hydrocarbons

Answer 11

when pure hydrocarbons are burnt completely, they are oxidised to carbon and water
eg. propane + oxygen –> carbon dioxide + water

Question 12

testing for water

Answer 12

blue cobalt chloride paper turns pink in contact with water

Question 13

testing for carbon dioxide

Answer 13

limewater turns cloudy

Question 14

incomplete combustion of hydrocarbons

Answer 14

In a limited supply of air, carbon monoxide many be produced.

Question 15

cracking

Answer 15

breaking down large hydrocarbon molecules into smaller ones

Question 16

2 ways to do cracking

Answer 16

steam cracking

catalytic cracking

Question 17

steam cracking

Answer 17

done by heating a mixture of hydrocarbon vapours and steam to a very high temperature

Question 18

catalytic cracking

Answer 18

done by passing hydrocarbon vapours over a hot catalyst

Question 19

thermal decomposition cracking

Answer 19

During cracking, thermal decomposition reactions produce a mixture of smaller molecules. Some are alkanes. These alkanes with smaller molecules are more useful as fuels. Also produces alkenes.

Question 20

alkenes

Answer 20

unsaturated hydrocarbons- contain fewer H atoms than alkanes with the same number of carbon atoms
Have a C-C double covalent bond in their molecules. This means they are more reactive than alkanes.
general formula C2n

Question 21

alkenes and bromine water

Answer 21

alkenes react with bromine water turning it from orange to colourless- this reaction is used as a test for unsaturated compounds.

Question 22

alkenes uses

Answer 22

used to produce polymers and other chemicals like solvents