Organic chemistry

Question 1

How was crude oil formed?

Answer 1

-Formed over millions of years ago from the fossilised remains of plankton

Question 2

Where is crude oil found?

Answer 2

Found in porous rocks in earths crust

Question 3

Crude oil is:

Answer 3

A finite resource that is used to produce fuse and other chemicals

Question 4

What are most of the compounds in crude oil?

Answer 4

Hydrocarbons

Question 5

hydrocarbons

Answer 5

Molecules made of only carbon and hydrogen atoms

Question 6

hydrocarbons….

Answer 6

Vary in size…

-Affects their properties and how they can be used as fuels

Question 7

The larger the hydrocarbon:

Answer 7

• more viscous it is
• higher boiling point
• less volatile it is
• less flammable

Question 8

fractional distillation

Answer 8

Separating crude oil into different fractions

Question 9

What do the fractions contain?

Answer 9

Each Fraction contains hydrocarbon molecules with a similar number of carbon atoms

Question 10

Most hydrocarbons obtained are…

Answer 10

alkanes

Question 11

Fractional distillation process:

Answer 11

• Crude oil is heated until evaporated
• Vapour moves up fractioning column
• Top is cooler than the bottom

Question 12

What happens to shorter hydrocarbons in fractional distillation?

Answer 12

Shorter hydrocarbons reach the top before they condense and are collected

Question 13

What happens to the longer hydrocarbons in fractional distillation?

Answer 13

longer hydrocarbons condense at higher temperatures and are collected lower down

Question 14

alkanes are

Answer 14

Saturated hydrocarbons

Question 15

alkane general formula:

Answer 15

CnH2n+2

Question 16

methane

Answer 16

1 carbon

4 hydrogen

Question 17

ethane

Answer 17

2 carbon

6 hydrogen

Question 18

propane

Answer 18

3 carbon

8 hydrogen

Question 19

most fuels=

Answer 19

compounds of carbon + hydrogen

many contain sulfur

Question 20

during combustion:

Answer 20

• carbon and hydrogen are oxidised
• energy is released
• waste products are produced + released into the atmosphere

Question 21

what happens if combustion is not complete?

Answer 21

carbon monoxide, unburnt fuels + solid particles containing soot may be released

Question 22

cracking

Answer 22

the process of turning longer chain hydrocarbon into shorter ones

Question 23

two methods of cracking hydrocarbons

Answer 23

• steam

- catalytic

Question 24

steam cracking:

Answer 24

• hydrocarbon are mixed with steam

- heated to 850°C

Question 25

catalytic cracking:

Answer 25

• hydrocarbon heated until vaporised

- vapour is passed over hot aluminium oxide catalyst

Question 26

products of cracking:

Answer 26

• alkanes

- alkenes

Question 27

bromine water

Answer 27

used to differentiate between alkanes + alkenes

Question 28

alkenes are…

Answer 28

more reactive than alkanes

Question 29

alkenes react..

Answer 29

when shaken with bromine water

turning from orange to colourless

Question 30

alkene + bromine water =

Answer 30

colourless solution

Question 31

alkene general formula

Answer 31

CnH2n