Chapter 9

Question 1

where is crude oil found?

Answer 1

rocks

Question 2

how is crude oil made?

Answer 2

remains of sea life were buried in mud
layers of rocks build up on top
this creates the high pressure and temperature needed for crude oil

Question 3

what conditions are needed for crude oil to form? 3

Answer 3

no oxygen
high temperature
high pressure

Question 4

what is crude oil?

Answer 4

a mixture of different carbon compounds

Question 5

what is a hydrocarbon?

Answer 5

compounds containing carbon and hydrogen

Question 6

what is a fraction?

Answer 6

different substances with similar boiling points found in crude oil

Question 7

how to separate fractions?

Answer 7

fractional distillation (heat, separate fractions and collect)

Question 8

formula and name of first alkane

Answer 8

methane CH4

Question 9

formula and name of second alkane

Answer 9

ethane C2H6

Question 10

formula and name of third alkane

Answer 10

propane C3H8

Question 11

formula and name of fourth alkane

Answer 11

butane C4H10

Question 12

how can you describe alkanes?

Answer 12

saturated hydrocarbons

Question 13

what is a saturated hydrocarbon?

Answer 13

it contains as many hydrogen atoms as possible in each molecule

Question 14

general formula of an alkane

Answer 14

Cn H(2n+2)

Question 15

which hydrocarbons burn and ignite best?

Answer 15

short chain hydrocarbons

Question 16

as the chain length increases, what happens to the boiling point of a hydrocarbon?

Answer 16

it increases

Question 17

as the chain length increases, what happens to the volality of a hydrocarbon?

Answer 17

it decreases

Question 18

what is the volality of a hydrocarbon?

Answer 18

the tendency of a substance to turn into a gas

Question 19

what is the viscosity of a substance?

Answer 19

how easily it flows

Question 20

as the chain length increases, what happens to the viscosity of a hydrocarbon?

Answer 20

it gets thicker (higher viscosity)

Question 21

what do the properties of each fraction depend on?

Answer 21

the size of the hydrocarbon molecules in it

Question 22

process of fractional distillation of crude oil

Answer 22

it is heated at the bottom of a tall column, which is cooler at the top
the gases move up the column when they reach boiling point and condense at the cooler temperature
they condense at different levels and are collected

Question 23

what are the products of complete combustion of hydrocarbons

Answer 23

carbon dioxide and water

Question 24

when does incomplete combustion occur

Answer 24

when there isnt enough oxygen

Question 25

what happens to the hydrocarbon when complete combustion occurs?

Answer 25

they are oxidised to form the products

Question 26

what is produced when incomplete combustion occurs?

Answer 26

carbon monoxide

Question 27

how to tell that a hydrocarbon is an alkane?

Answer 27

it has a c-c single bond

Question 28

two tests for water?

Answer 28

turns cobalt chloride paper pink

turns white anhydrous copper sulphate blue

Question 29

why are hydrocarbons cracked?

Answer 29

the longer chainlengths aren’t in high demand but the shorter ones are, so they are broken down to form these desirable chainlengths

Question 30

process of cracking

Answer 30

the fraction is heated to vaporise the hydrocarbons
the vapour is then heated to a very high temperature
thermal decomposition takes place, turning the larger molecules into smaller ones

Question 31

how to tell that a hydrocarbon is an alkene?

Answer 31

has a double c=c bond

Question 32

are alkenes saturated or unsaturated?

Answer 32

unsaturated, compared to alkanes they have less 2 hydrogens for the carbon to bind to

Question 33

why are alkenes more reactive?

Answer 33

the double bond opens up to form a single bond and allow the carbon to bond to other atoms

Question 34

general formula for alkenes

Answer 34

Cn H2n

Question 35

first four alkenes

Answer 35

ethene
propene
butene
pentene

Question 36

what happens when an alkene reacts with oxygen?

Answer 36

if there is enough oxygen, it will undergo complete combustion, however alkenes are very likely to undergo incomplete combustion

Question 37

what is produced when an alkene undergoes incomplete combustion

Answer 37

carbon, carbon monoxide, carbon dioxide and water

Question 38

what does the flame look like of something undergoing incomplete combustion

Answer 38

it will burn a smokey yellow flame

Question 39

what is the test for an unsaturated hydrocarbon (an alkene)?

Answer 39

it turns orange bromine water colourless