hydrocarbons

Question 1

what kind of resource is crude oil and where is it found

Answer 1

• finite resource

- rocks

Question 2

how were crude oils formed

Answer 2

1. remains of dead animals were buried in the mud

2. layers of rock formed on top of them creating a high pressure

Question 3

what is a crude oil

Answer 3

crude oil is a mixture of different hydrocarbon compounds

Question 4

what is the boiling point of crude oil

Answer 4

they are different as they contain a mixture of hydrocarbons with different boiling points

Question 5

what is a fraction

Answer 5

a group of hydrocarbons with similar boiling points

Question 6

how can crude oil be separated

Answer 6

with fractional distillation

Question 7

what is an alkane

Answer 7

a saturated hydrocarbon with single C-C bonds with the formula of CnH2n+2

Question 8

properties of shot chain hydrocarbons

Answer 8

• lower boiling point
• higher volatility (tendency to turn into gas)
• low viscosity (how easily it flows)
• higher flammability

Question 9

properties of long chain hydrocarbons

Answer 9

• high boiling point
• lower volatility (tendency to turn into gas)
• high viscosity (how easily it flows)
• lower flammability

Question 10

what is the purpose of fractional distillation

Answer 10

to separate crude oil into hydrocarbons with similar boiling points

Question 11

what is the order of a fractionating column

Answer 11

1. refinery/petroleum
2. gasoline/petrol
3. kerosine
4. diesel
5. residue

Question 12

what is volatility

Answer 12

how easily a substance turns into a gas

Question 13

what is viscosity

Answer 13

how easily a substance flows

Question 14

what are the most useful hydrocarbons

Answer 14

short chain hydrocarbons

Question 15

what are the products of the complete combustion of a hydrocarbon

Answer 15

carbon dioxide + water

Question 16

what is incomplete combustion and what are the products formed

Answer 16

when there is not enough oxygen to oxidise the hydrocarbon, carbon monoxide and water are produced

Question 17

where does cracking occur

Answer 17

in an oil refinery in stell vessels called crackers

Question 18

what happens to a large fraction after it has been distilled from a crude oil

Answer 18

it is either

• passed over a hot catalyst
• mixed with steam and heated to a very high temperature

Question 19

what kind of reactions take place as large hydrocarbons are cracked

Answer 19

thermal decomposition as larger hydrocarbons slip apart into smaller hydrocarbons which are more useful

Question 20

what is an alkene

Answer 20

a hydrocarbon with at least one C=C double covalent bond

Question 21

what kind of structure does an alkene have

Answer 21

it is unsaturated and has less hydrogen atoms in their molecules than alkanes.

Question 22

which are more reactive, alkenes or alkanes

Answer 22

alkenes because they have the ability to create new bonds

Question 23

how would you crack and alkene in a lab and test for the results

Answer 23

1. heat a test tube with ceramic wool soaked in medicinal paraffin and a catalyst with a delivery tube into a water basin.
2. the end of the delivery tube is underneath a boiling tube which contains water some way up

Question 24

what is a positive test for an unsaturated hydrocarbon

Answer 24

it turns orange bromine water colourless

Question 25

what is the order of alkenes and alkanes

Answer 25

methane - ene
ethane - ene
propane - ene
butane - ene
pentane - ene
hexane - ene
heptane - ene
octane - ene
nontane - ene
decane - ene

Question 26

why are alkanes used as fuels and not alkenes

Answer 26

because alkanes provide more energy per mole when combusted

Question 27

how would you test if something is a alkane or alkene

Answer 27

relight a glowing splint with the gas. If the flame is yellow and smokier it means that the gas is an alkene due to incomplete combustion.