Organic Chemistry

Question 1

Uses of petroleum gas

Answer 1

A fuel for heating and cooking especially stove gas

Question 2

Use of petrol/gasoline

Answer 2

Fuel in cars

Question 3

Uses for naphtha (heavy gasoline)

Answer 3

the feedstock and main source of hydrocarbons used for the production of a wide range of organic compounds in the petrochemical industry e.g diaper, plastic, detergent

Question 4

Uses for kerosene/paraffin

Answer 4

A fuel for heating and cooking and for aircraft engines

Question 5

Uses for diesel

Answer 5

A fuel for diesel engines

Question 6

Uses of Lubricating oil

Answer 6

Lubricants and as a source of polishes and waxes

Question 7

Uses for Bitumen

Answer 7

Making road surfaces

Question 8

Describe and explain how crude oil/ petroleum is separated.

Answer 8

Petroleum is separated by fractional distillation as it is a mixture of different hydrocarbons which have diff boiling point.

The crude oil is heated to evaporate the different fractions.

Gaseous fractions enter the bottom of the fractionating column which has a temperature gradient of reducing temperature with height.

At different level in the column, diff fractions are cooled down to their bp and condense and collected.

Heavier fractions with higher bp thus will be collected near the bottom of the column

Lighter fractions with lower bp will he collected near the top

Question 9

Why crude oil needs to be conserved?

Answer 9

It is a finite resource and need to eh conserved for the future generations.
However, the world is heavily dependent on fossil fuels. There is a world wide competing use of crude oil as energy source and as chemical feedstock.

Question 10

Formula of alkane

Answer 10

CnH2n+2 where n >/= 1

Question 11

Chemical properties of alkane

Answer 11

1 undergo complete combustion to form CO2 and H2O
2. Undergo substitution where alkane react with halogen under UV light to form halo-alkane AND hydrogen halide

Question 12

Importance of cracking

Answer 12

1. Produces more useful smaller, short chain hydrocarbons as they are more efficient ad fuel and chemical feedstock

2 improve supply of short chain hydrocarbons where long chain hydrocarbon are cracked to form short chain hydrocarbon thus supply can meet demand

Question 13

Types of addition of alkenes

Answer 13

1. Hydrogenation
2. Bromination
3. Hydration
4. Addition polymerisation

Question 14

What is hydrogenation and conditions for it?

Answer 14

Adding H2 to alkene to form alkane.
Condition: 200 degree celsius, nickel catalyst

Question 15

Application of hydrogentation

Answer 15

Manufacturing margarine
1. H2 is added to polyunsaturated vegetable oil
2. Under the condition of 200 deg celsius and nickel catalyst
3. H2 added across C double bonds
4. Mr of vegetable oil increase
5. Melting point of veg oil increase
6. Solid margarine formed

Question 16

What is bromination

Answer 16

It is the addition of Br2 to alkenes to form bromo-alkane

Question 17

Application of bromination

Answer 17

Test the presence of alkenes
Bromine decolourises when added to alkenes to form colourless bromo-alkane

Question 18

What is hydration and its conditions?

Answer 18

Hydration is the addition of STEAM to alkene to form alcohol.

Condition: 300 degree celsisus, 60 atm, H3PO4 acid as catalyst

Question 19

What are the physical propertes of alcohol

Answer 19

• volatile liquids at rtp
• as C atoms per molecule increases, mp/bp increases
• as C atoms per molecules increases, solubility in H2O decreases due to stronger FOA betwen larger and heavier molcules
• flammability decreases, harder for alcohol to vapourise

Question 20

Chemical properties of alcohol

Answer 20

• complete combusition to form CO2 anf H2O
• can be oxidised to carboxylic acid and H2O formed in the process by:
  oxidation by bacteria +O2
  oxidised by OA
• Esterfication

Question 21

Uses of ethanol

Answer 21

1. fuel for vehicle
2. solvents for paints,perfume, varnishes and other organic substances
3. constituents of alcoholic drinks

Question 22

How is ethanol formed?

Answer 22

• Hydration of ethene
• fermentation of glucose with yeast in the absence of O2. Condition: 37 degrees celsius

Eqn of the fermentation of glucose
C6H12O6—->2C2H5OH+2CO2

Question 23

Why is the fermentation of glucose to form ethanol occur in the absence of oxygen?

Answer 23

Oxygen will oxidise ethanol into carboxylic acid

Question 24

Chemical properties of carboxylic acid

Answer 24

• weak monobasic acid
• esterfication (alcohol+carboxylic acid–>ester+H2O)

Question 25

Application of esters

Answer 25

• colourless,neutral liquids insoluble in water
• good organic solvent
• has a sweet fruity smell and hence often used in perfumes

Question 26

How does esters form?

Answer 26

Alcohl lose O atom, carboxylic acid lose OH atoms to form a ester group COO-

Question 27

What are macromolecules?

Answer 27

Macromolecules are large molecules built up from small units called monomers covalently bonded.

Question 28

What is addition polymerisation.

Answer 28

The addition of unsaturated compounds together to form a large molecule without the losing any atoms or molecules.

Question 29

Uses of terylene (polyesters)

Answer 29

• make into clothes
• make sails
• make sleeping bags

Question 30

Uses of nylon(polyamide)

Answer 30

• woven into cloth to make nylon tents, parachutes and raincoat
• made into fibres to make strong ropes and fishing lines
• make strong zippers