4(a, b, c, d)

Question 1

Describe Empirical formula?

Answer 1

Gives the simplest whole number ratio of the atoms in a compound. E.g (CH2)

Question 2

Describe Molecular formular?

Answer 2

Shows the actual number of each type of atom present. E.g (C3 H6)

Question 3

Describe Structular formular?

Answer 3

Shows how the atom is joined together in a molecule. E.g (CH2)3

Question 4

Describe Displayed and Skeletal?

Answer 4

Displayed shows all the bonds as a single line while skeletal is a very simplified version of displayed.

Question 5

What is a homologous series?

Answer 5

A series of compounds with similar chemical properties because they have the same functional group. Example; Alkanes, alkenes, alcohols.

Question 6

What is a functional group?

Answer 6

A functional group is an atom or group of atoms that determine the chemical properties of a compound. Example; functional group for alcohols is the -OH group and for alkenes is C=C.

Question 7

What does saturated mean in chemical terms?

Answer 7

Only single bonds present. No double bonds.

Question 8

Describe an Alkane?(2)

Answer 8

Cn H2n+2. Carbon-Carbon single bond.

Question 9

Describe an Alkene?(2)

Answer 9

Cn H2n. Carbon=Carbon double bond.

Question 10

Describe an Alkyne?(2)

Answer 10

Cn H2n-2. Carbon≡Carbon triple bond.

Question 11

Describe an Alchohol?(2)

Answer 11

Cn H2n OH. Oxygen-Hydrogen bond.

Question 12

What is a structural Isomer?

Answer 12

A structural isomer is a compound with same molecular formula but different structural formula.

Question 13

State how to test for an Alkene or Alkane?

Answer 13

The Bromine Water test. When you shake an Alkene with orange bromine water the solution becomes colourless.
When you shake an alkane with orange bromine water the solution will stay orange.

Question 14

The crude oil fractions with the lowest boiling point…

Answer 14

Are the least viscous and most flammable, the fractions with the highest boiling point are the most viscous and least flammable.

Question 15

State all the fractions of crude oil from least flammable to most flammable.

Answer 15

Bitumen, Fuel oil, Diesel oil, Kerosine, Gasoline, Refinery gases.

Question 16

State the uses of Refinery gases and Gasoline?

Answer 16

Heating and vehicles such as cars respectively .

Question 17

State the uses of Kerosine and Diesel oil?

Answer 17

Fuel for aircraft and diesel vehicles respectively.

Question 18

State the uses of Bitumen and fuel oil?

Answer 18

Asphalt for roads and steam boilers in power plants.

Question 19

Describe a Carboxylic Acid?

Answer 19

Cn H(2n+1)OH.

Question 20

Explain how the combustion of hydrocarbon fuels results in the formation of Sulphur Dioxide?

Answer 20

A lot of the hydrocarbon fractions have sulphur impurities which is why when they’re burnt, sulphur dioxide is produced.

Question 21

Explain how the combustion of hydrocarbon fuels results in the formation of Nitrogen oxides?(2)

Answer 21

When temperatures are high enough for the nitrogen and oxygen in the air to react Nitrogen oxides are created from hydrocarbon fractions. This often happens in car engines.

Question 22

How does Sulphur Dioxide and oxides of Nitrogen contribute to acid rain?(2)

Answer 22

When sulphur dioxide and nitrogen oxides mix with the water vapour in clouds, they form dilute sulphuric or nitric acids. This falls as acid rain.

Question 23

How do Halogens react with Alkanes?(2)

Answer 23

In the presence of ultraviolet light Chlorine and Bromine react with Alkanes to make Haloalkanes. This is called a substitution reaction because the hydrogen atom is substituted.

Question 24

What are the prefixes for the No. of Carbons from 1 - 6?(6)

Answer 24

1. Meth-
2. Eth-
3. Prop-
4. But-
5. Pent-
6. Hex-

Question 25

Describe how crude oil is separated into different hydrocarbon fractions?(5)

Answer 25

Crude oil is heated until most of it is gas, this gas enters a fractioning column.
In the column there is a temperature gradient. When the substances that make up the crude oil reach a part where the temperature is lower than their boiling point they condense.
The longer hydrocarbons have higher boiling points. They condense and drain out of the column early on near the bottom and the opposite for the shorter hydrocarbons.
Bubble caps in the fractioning column prevent the separated liquids from running back down and remixing.
You end up with the crude oil mixture separated out into different fractions.

Question 26

What are two requirements for cracking to take place?(3)

Answer 26

A temperature of 600-700 degrees and a catalyst. Cracking is a form of thermal decomposition.

Question 27

What are the catalysts used in industry cracking?(2)

Answer 27

Silica(SiO3) or Alumina(Al2O3)

Question 28

What are the products of Complete and Incomplete Combustion?(2)

Answer 28

For complete combustion Carbon Dioxide and Water are produced.
For incomplete combustion Carbon Monoxide, Water and Carbon in the form of Soot can be produced.

Question 29

How does Bromine react with Alkenes?

Answer 29

Bromine adds to alkenes without any need of heat, or light or catalyst. Usually Bromine water is used.
Bromine water is orange but the product is a colourless liquid called 1,2 - dibromoethane.