Intro to Organic Chem

Question 1

How is petroleum separated into fractions?

Answer 1

Fractional distillation, fractions of petroleum have different boiling points.

Question 2

Why is petroleum separated into fractions?

Answer 2

Before separation, petroleum contains large mixture of hydrocarbons of varying lengths. Thus, it will be less efficient fuel, resulting in sootier and smokier flame when burnt due to incomplete combustion (C, CO, CO2)

Question 3

Steps of fractional distillation of petroleum

Answer 3

1. The petroleum is first heated into vapour.
2. The vapour passed up the fractioning column.
3. The fractions condense out of different heights depending on their boiling points.
4. Lighter fractions contain molecules with lower molecular masses, hence less dense and have lower boiling point. They will come out as fractions near the top of the column. Heavier fractions contain molecules with higher molecular mass hence denser and have higher boiling point will come out as fractions near the bottom of the column.

Question 4

Fractions in petroleum

Answer 4

Petroleum gas
Petrol/ Gasoline
Naphtha
Kerosene/Paraffin
Diesel
Lubricating oil
Bitumen

Question 5

Use of petroleum gas

Answer 5

Fuel for cooking and heating

Question 6

Use of petrol/gasoline

Answer 6

Fuel for car engines

Question 7

Naphtha

Answer 7

Used as chemical feedstock for chemical industry

Question 8

Kerosene/Paraffin

Answer 8

Fuel for aircraft engine

Fuel for domestic cooking and heating

Question 9

Diesel

Answer 9

Fuel for diesel engines in buses, lorries and trains

Question 10

Use of lubricating oil

Answer 10

As lubricants for machines and as sources of waxes and polishes

Question 11

Use of bitumen

Answer 11

For making road surfaces

Question 12

Issues with use of petroleum

Answer 12

1. Pollution and global warming

2. Petroleum is non-renewable and finite, resulting in competing use.

Question 13

Ways to conserve petroleum

Answer 13

1. Reduce the use of petroleum
   - reducing the number of vehicles on the road
   - drive smaller cars that consume less petrol
   - take public transport instead
2. Use alternative energy sources
   - solar energy
   - nuclear energy
   - Biofuel
3. Improve design of power stations and vehicles so that they use petroleum more efficient

Question 14

Definition of hydrocarbons

Answer 14

Hydrocarbons are organic compounds that contain hydrogen and carbon only.

Question 15

Definition of homologous series

Answer 15

A family of organic compounds with the same functional group and similar chemical properties

Question 16

Definition of functional group

Answer 16

An atom or a group of atoms that give a molecule its characteristic chemical properties

Question 17

Characteristics of organic compounds in the same homologous series

Answer 17

1. Same general formula
2. Similar chemical properties (as they have the same functional group)
3. Differ from the successive member by a -CH2 group
4. Gradual change in their physical properties

Question 18

Melting and boiling point increases down the group.

Answer 18

As their molecular sizes increases, the number of electrons increases, the intermolecular forces of attraction is stronger, a higher amount of energy is required to overcome the stronger intermolecular forces of attraction hence melting and boiling point increases.

Question 19

Increase in viscosity

Answer 19

Molecular sizes increases, the number of electrons increases, stronger intermolecular forces of attraction hence flow less easily.

Question 20

Flammability decreases

Answer 20

As their molecular sizes increases, the number of electrons increases, the intermolecular forces of attraction is stronger, a higher amount of energy is required to overcome the stronger intermolecular forces of attraction hence boiling point increases, thus, less volatile and less flammable.

Question 21

Prefix

Answer 21

Denotes substituents/ side groups

Question 22

Parent

Answer 22

Denotes largest continuous carbon chain bearing as the principal functional group

Question 23

Suffix

Answer 23

Denotes principal functional group