Paper 2 - Organic

Question 1

Crude Oil?

Answer 1

refined crude oil in rocks. Crude oil is a finite resource (if we continue using it, then crude oil will one day run out)

Question 2

how was crude oil formed?

Answer 2

From the remains of tiny sea creatures called plankton, which were buried in mud, over millions of years ago

Question 3

hydrocarbon?

Answer 3

Are molecules made up with hydrogen and carbon atoms only e.g. Methane CH4

    H   H—C—H
    H

Question 4

What is crude oil a mixture of?

Answer 4

Molecules called hydrocarbons e.g. Methane CH4

Question 5

what is an alkane?

Answer 5

scientist say they are saturated molecules.

They have a general formul CnH2n+2
This is because if we know the number of carbon atoms in the alkane (n) then we can calculate the number of hydrogen atoms

Question 6

Ethane?

Answer 6

C2H6

      H   H    H—C—C—H
     H    H

Question 7

Propane?

Answer 7

C3H8

     H    H    H    H—C—C—C—H
     H    H    H

Question 8

Butane?

Answer 8

C4H10

       H   H   H   H
H—C—C—C—C—H
      H    H   H   H

Question 9

what is viscosity?

Answer 9

Tells us the thickness of a fluid

Question 10

What happens as the size of the hydrocarbon molecules increase e.g. Methane ➡️ Ethane ➡️ Propane etc?

Answer 10

the molecules get more viscous (thicker and move more slowly)

Question 11

Flammability?

Answer 11

Tells us how easily a hydrocarbon combusts (burns)

Question 12

Are short chain hydrocarbons flammable?

Answer 12

Yes extremely flammable
That’s why we use Methane in bunsen burners

Question 13

The longer the chain of hydrocarbons…?

Answer 13

The more difficult they are to burn

Question 14

Do short chain hydrocarbons have a low or high boiling point?

Answer 14

Low boiling point e.g. All the 4 hydrocarbons are gas at room temperature

Question 15

When do hydrocarbon fuels release energy?

Answer 15

when combusted (burned)

Question 16

What happens during combustion of fuel?

Answer 16

the carbon and hydrogen atoms in the fuel react with oxygen. They are oxidised

Question 17

Complete combustion?

Answer 17

During combustion, if the oxygen is unlimited, the reaction produces water and carbon dioxide

Question 18

In fractional distillation what is crude oil separated into?

Answer 18

fractions. Fractions contain hydrocarbons with a similar number of boiling points

Question 19

Fractional distillation to seperate crude oil?

Answer 19

Firstly the crude oil is heated to a very high temperature which causes it to boil (all of the hydrocarbons evaporate and turn into a gas). The crude oil vapour is now fed into the fractional distillation column. It it hotter at the bottom but cooler at the top. The hydrocarbon vapours now rise up the column. When the hydrocarbons condense, the liquid fractions are then removed. The remaining hydrocarbons continue moving up the column. They condense when they reach their boiling points.

Question 20

What hydrocarbons will condense higher up the fractional distillation column?

Answer 20

Methane, Ethane etc

Question 21

What are some fractions used for?

Answer 21

Fuels

Question 22

What is another way that some fractions are used?

Answer 22

As feedstock (a chemical that is used to make other chemicals) for the petrochemical industry e.g. solvents, lubricants

Question 23

due to the high demand for short chain hydrocarbons to be used as fuels because they are more flammable, for example, how do you convert long chain hydrocarbons into shorter chain hydrocarbons?

Answer 23

A process called cracking, where a long chain alkane is broken down (cracked) to produce smaller, more useful molecules

Question 24

What is catalytic cracking?

Answer 24

We use high temperature and a catalyst. The job of the catalyst is the speed up the reaction.

Question 25

What is steam cracking?

Answer 25

We use high temperature and steam

Question 26

Property of an alkene?

Answer 26

have a double covalent bond between two carbon atoms
e.g. H H
C — C (two lines)
H H

Question 27

why are alkenes useful?

Answer 27

they are used to make chemicals called polymers

Question 28

what is the difference between alkenes and alkanes?

Answer 28

Alkenes are more reactive than alkanes

Question 29

How to test for alkanes?

Answer 29

using bromine water, which is orange. if we shake our alkene with bromine water, then the bromine water turns colourless

Question 30

Which hydrocarbons have lower boiling points?

Answer 30

Those with a lower chain of hydrocarbon molecules