C9 - Crude oil

Question 1

crude oil

Answer 1

finite resource found in rocks
-formed by remains of small sea animals/plants + pressurised rock
-mixture of different hydrocarbons

Question 2

hydrocarbons

Answer 2

-compounds containing only hydrogen and carbon atoms

Question 3

fractions

Answer 3

-before use, crude oil is split into different substances with similar boiling points

Question 4

distillation

Answer 4

-separates substances with different boiling points

Question 5

alkanes

Answer 5

-saturated hydrocarbons
-contains max hydrogen atoms

Question 6

formula for alkane

Answer 6

CnH(2n+2)
-for every n carbon atoms there are (2n+2) H atoms

Question 7

short chain molecule hydrocarbons (5)

Answer 7

-lower boiling point
-ignite + burn better
-more volatile
-low viscosity = runny
-higher flammability

Question 8

why are short chain hydrocarbons more useful

Answer 8

-burn better
-with cleaner, less smoky flames
-useful fuels

Question 9

viscosity

Answer 9

low = good ability to flow
-the internal friction of a moving fluid

Question 10

Long chain hydrocarbon properties (4)

Answer 10

-higher boiling point
-less volatile
-thick = high viscosity
-lower flammability

Question 11

Fractional distillation

Answer 11

-each hydrocarbon fraction = similar boiling point
-due to diff size molecules
-collected at diff levels as gas condenses

Question 12

Fractional distillation - smallest molecules

Answer 12

-lowest boiling point
-pumped from cooler top of gas
-lighter fractions

Question 13

Where are lighter fractions used

Answer 13

-combustion

Question 14

products of complete combustion

Answer 14

-water
-co2

Question 15

Test for complete combustion - water

Answer 15

-turns blue cobalt chloride paper pink
-or white anhydrous copper sulfate blue

Question 16

Test for complete combustion - co2

Answer 16

-turns limewater cloudy

Question 17

Incomplete combustion

Answer 17

-less oxygen
-some carbon atoms form CO instead of co2

Question 18

Carbon monoxide danger

Answer 18

-odourless
-colourless
-toxic
-carried around body instead of o2

Question 19

cracking

Answer 19

-larger, less useful hydrocarbons are broken down into smaller ones

Question 20

Heavier fractions

Answer 20

-made from larger molecules
-difficult to vaporise
-do not burn easily (poor fuels)

Question 21

In the cracker

Answer 21

-heavy fractions heated to vaporise hydrocarbons
-vapour is passed over hot catalyst or
-mixed w steam + heated

Question 22

Cracking reaction

Answer 22

thermal decomposition
-larger to smaller molecules

Question 23

alkene product

Answer 23

-product made from cracking

Question 24

alkene meaning

Answer 24

-unsaturated compounds containing at least one double bond between carbon atoms
-2 fewer H atoms than alkanes

Question 25

Alkene properties

Answer 25

-burns in air, not as well as small alkane
-react with bromine water
-more reactive than alkanes

Question 26

How to test for alkene

Answer 26

-turns bromine water from orange to colourless
-alkanes do not react with bromine water