c9 - crude oils

Question 1

what are fossil fuels made of

Answer 1

formed from the remains of organic matter

Question 2

types of fossil fuels

Answer 2

crude oil, natural gas, coal

Question 3

fuel + oxygen

Answer 3

-> water + carbon dioxide

Question 4

hydrocarbon

Answer 4

molecules made up of just hydrogen and carbon atoms
- they differ in size, which alters their properties

Question 5

alkanes and their properties

Answer 5

• end in -ane
• general formula: CnH2n+2
• low reactivity
• complete combustion therefore useful as fuels
• saturated hydrocarbon

Question 6

crude oil

Answer 6

a mixture of hydrocarbons

Question 7

first ten alkanes

Answer 7

methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane

Question 8

saturated hydrocarbon

Answer 8

it does not have a double bond; an alkane

Question 9

viscosity

Answer 9

being thicker and flowing easily

Question 10

viscosity of hydrocarbons

Answer 10

• longer chain: higher viscosity
• lower chain: lower viscosity

Question 11

boiling point of hydrocarbons

Answer 11

• longer chain: higher boiling point
• short chain: lower boiling point

Question 12

flammability

Answer 12

• longer chain: less flammable
• short chain: more flammable

Question 13

volatility

Answer 13

how easily it evaporates

Question 14

volatility of hydrocarbons

Answer 14

long chain: high volatility
short chain: low volatility

Question 15

uses of crude oil

Answer 15

• tarmac
• fuels

Question 16

unsaturated hydrocarbon

Answer 16

has a double bond; an alkene

Question 17

fractional distillation

Answer 17

the process of separating crude oil into groups of hydrocarbons with similar numbers of carbon atoms “fractions”

Question 18

what are long chain and short chain hydrocarbons?

Answer 18

• long-chain: has lots of carbon atoms
• short-chain:few carbon atoms

Question 19

explain the process of fractional distillation

Answer 19

EVAPORATION:
- evaporate the crude oil by heating it
- crude oil vapour is put into a fractionating column at the bottom and it rises upwards
CONDENSATION:
- temp is highest at the bottom and lowest and gets colder at the top
- LONG-CHAIN hydrocarbons condense at the bottom and are collected as liquids
- SHORT-CHAIN hydrocarbons have lower boiling points so they pass up the column at lower temps near the top
COLLECTION:
- the fractions are then collected and processed to create end products: fuel or feedstock

Question 20

feedstock

Answer 20

materials used in an industrial process to make products

Question 21

incomplete combustion

Answer 21

• if alkanes are burnt without enough oxygen, then carbon monoxide is released
  2C + O2 => 2CO

Question 22

properties of carbon monoxide

Answer 22

• colourless
• toxic
• odourless

Question 23

complete combustion

Answer 23

• involves the release of energy (hence good fuels)
• the oxidation of carbon and hydrogen => dioxide and water

Question 24

why do heavy fractions of crude oil not create good fuels?

Answer 24

• they have high boiling points
• don’t ignite easily
• have low volatility

Question 25

cracking

Answer 25

the process that breaks down long-chain molecules into shorter-chain that are more useful
- an example of thermal decomposition

Question 26

two types of cracking

Answer 26

catalytic cracking and steam cracking

Question 27

what is catalytic cracking

Answer 27

• vapourised heavy hydrocarbons are passed over the top of a heated (zeolite) catalyst
• alkanes and alkenes are produced by the reaction eg. hexane => butane + ethene

Question 28

what is steam cracking

Answer 28

• vapourised heavy hydrocarbons are combined with steam in a high temperature environment
• alkanes and alkenes are produced eg. decane => octane + ethene

Question 29

uses of alkenes

Answer 29

• starting materials for chemicals like ethanol
• being combines to make polymers