Fuels

Question 1

what are hydrocarbons?

Answer 1

compounds which ONLY contain hydrogen and carbon

Question 2

what is crude oil?

Answer 2

a natural resource that is a complex mixture of hydrocarbons

Question 3

why is crude oil considered a finite resource? (2)

Answer 3

-it forms extremely slowly over millions of years
-cannot quickly be replaced

Question 4

what do crude oils contain (their structure)?

Answer 4

molecules in which carbon atoms are in chains or rings

Question 5

what are crude oils needed for? (2)

Answer 5

-fuels
-feedstock for the petrochemical industry

Question 6

what can crude oil be separated using?
why?

Answer 6

fractional distillation
-different hydrocarbons have different boiling points

Question 7

describe the fractional distillation of crude oils? (4)

Answer 7

-heated crude oil enters near the bottom of a tall fractionating column, which is hot at the bottom and gets cooler towards the top
-vapours from the oil rise through the column
-vapours condense when the temperature of the column is cool enough
-liquids are led out of the column at different heights

Question 8

what happens to hydrocarbons with low melting points?

Answer 8

They do not condense but leave the column as gases

Question 9

what are gases used for?

Answer 9

used in domestic heating and cooking

Question 10

what is petrol used for?

Answer 10

used as fuel for cars

Question 11

what is kerosene used for?

Answer 11

used as fuel for aircraft

Question 12

what is diesel oil used for?

Answer 12

used as fuel for some cars and trains

Question 13

what are fuel oils used for?

Answer 13

used as fuel for large ships and in some power
stations

Question 14

what is bitumen?

Answer 14

used to surface roads and roofs

Question 15

description of small molecules that are crude oil fractions?

Answer 15

-low boiling point
-very volatile
-flow easily
-ignites easily

Question 16

description of large molecules that are crude oil fractions?

Answer 16

-high boiling point
-not very volatile
-does not flow easily
-does not ignite easily

Question 17

one way to remember the name of the fractions?

Answer 17

‘Good Penguins Keep Diving For Bass

Question 18

what are alkanes?

Answer 18

saturated hydrocarbons
-contain only single carbon bonds

Question 19

describe the properties of a homologous series?

Answer 19

-have the same general formula
-differ by CH2 in the molecular formula of neighbouring compounds
-show a gradual variation in physical properties, such as their boiling points
-have similar chemical properties

Question 20

explain why as the number of carbon atoms increases, so does the boiling point: (3)

Answer 20

-the intermolecular forces between alkane molecules become stronger
-more energy is needed to overcome these forces
-the boiling point increases

Question 21

which formula do all alkanes fit?

Answer 21

CnH2n+2

Question 22

when does complete combustion of hydrocarbons happen?

Answer 22

when there is a good supply of air

Question 23

which type of reaction is complete combustion?

Answer 23

exothermic

Question 24

equation for the complete combustion of a hydrocarbon:

Answer 24

Hydrocarbon + oxygen → carbon dioxide + water

Question 25

when does incomplete combustion happen?

Answer 25

when the oxygen supply is poor

Question 26

equation for incomplete combustion of a hydrocarbon: (2)

Answer 26

hydrocarbon + oxygen → carbon monoxide+ water

hydrocarbon + oxygen → carbon + water

Question 27

what is carbon released as in incomplete combustion? (2)

Answer 27

fine black particles
-that are deposited as soot

Question 28

what can soot cause? (2)

Answer 28

breathing problems and it blackens buildings

Question 29

why is carbon monoxide dangerous? (3)

Answer 29

-toxic gas.
-absorbed in the lungs and binds with the haemoglobin in the red blood cells.
-this reduces the capacity of the blood to carry oxygen.

Question 30

side effect of carbon monoxide poisoning: (2)

Answer 30

drowsiness, and affected people may fall unconscious or even die.