12.2 FRACTIONAL DISTILLATION OF CRUDE OIL

Question 1

What is crude oil at present the world’s main source?

Answer 1

main source of organic chemicals

Question 2

Why is crude oil called a fossil fuel?

Answer 2

as it was formed millions of years ago by temperatures deep below the Earth’s surface

Question 3

Why is crude oil non-renewable?

Answer 3

it forms very slowly

Question 4

What is crude oil a mixture of?

Answer 4

mixture of mostly alkanes, both unbranched and branched

Question 5

Do crude oil from different sources have different compositions?

Answer 5

yes

Question 6

What does crude oil also contain?

Answer 6

small amounts of other compounds dissolved in it

Question 7

Where does the small amount of other compounds dissolved in crude oil come from?

Answer 7

come from other elements in the original plants and animals the oil was formed from

Question 8

Example of compound dissolved in crude oil?

Answer 8

sulphur

Question 9

What does sulphur produce when burnt?

Answer 9

sulphur dioxide, SO2

Question 10

What does sulphur dioxide cause?

Answer 10

acid rain

Question 11

How does sulphur dioxide cause acid rain? (2)

Answer 11

sulphur dioxide reacts with oxygen high in the atmosphere to form sulphur trioxide

sulphur trioxide reacts with water in the atmosphere to form sulfuric acid

Question 12

What must be done to convert crude oil into useful products?

Answer 12

have to separate the mixture

Question 13

How is crude oil separated?

Answer 13

done by heating and collecting the fractions that boil over different ranges of temperatures

Question 14

What is each fraction from crude oil? (hint- mixture of what)

Answer 14

mixture of hydrocarbons of similar chain length and so similar properties

Question 15

What is the process of how crude oil is separated into its fractions called?

Answer 15

fractional distillation

Question 16

Where is fractional distillation done?

Answer 16

in a fractionating tower

Question 17

What is first done to crude oil before its fractionated?

Answer 17

heated in a furnace

Question 18

What happens after the crude oil is heated in a furnace?

Answer 18

mixture of liquid and vapour passes into a tower that’s cooler at the top than at the bottom

Question 19

What happens after the mixture of liquid and vapour passes into a tower?

Answer 19

vapour passes up the tower via a series of trays containing bubble caps until they arrive at a tray that’s sufficiently cool (lower temp than their boiling pt.). then they condense to liquid

Question 20

What happens after the fractions have condensed on each tray?

Answer 20

they’re piped off

Question 21

At which trays do shorter chain hydrocarbons condense?

Answer 21

trays closer to the top of the tower, where it’s cooler

Question 22

Why do shorter chain hydrocarbons condense at trays closer to the top?

Answer 22

because they have lower boiling points

Question 23

What is collected at the base of the tower?

Answer 23

thick residue

Question 24

What is the thick residue collected at the base of the tower called?

Answer 24

tar or bitumen

Question 25

What can tar/ bitumen be used for?

Answer 25

road surfacing

Question 26

What happens to tar/ bitumen?

Answer 26

as supply often exceeds demands, this fraction often further processed to give more valuable products