Unit 2 i) Hydrocarbons

Question 1

Name the 3 fossil fuels?

Answer 1

Coal Oil Gas

Question 2

Fossil fuels are finite. What does finite mean?

Answer 2

This means that they will eventually run out

Question 3

What is combustion?

Answer 3

Combustion is a chemical reaction where substances burn in the presence of oxygen

Question 4

What word is used to describe a reaction that gives out heat?

Answer 4

Exothermic

Question 5

What is an endothermic reaction?

Answer 5

A reaction that takes in energy.

Question 6

What is a fossil fuel?

Answer 6

Fuel from remains of long dead animals or plants. eg coal oil gas

Question 7

What is the test for hydrogen?

Answer 7

Burns with a pop

Question 8

What is the test for oxygen?

Answer 8

Relights a glowing splint

Question 9

What is the test for carbon dioxide?

Answer 9

Turns lime water milky

Question 10

What is a hydrocarbon?

Answer 10

A substance that contains only hydrogen and carbon

Question 11

What is the simplest alkane?

Answer 11

Methane

Question 12

What is the general formula of the alkanes?

Answer 12

CnH2n+2

Question 13

What is a fuel?

Answer 13

A fuel is a substance which has stored energy. This energy is released when a fuel is burned

Question 14

What is made when alkanes burn in excess oxygen?

Answer 14

Carbon dioxide and water

Question 15

Name the alkanes and formulas from 1 to 8 carbons

Answer 15

Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10 Pentane C5H12 Hexane C6H14 Heptane C7H16 Octane C8H18

Question 16

What do all alkenes contain?

Answer 16

A carbon to carbon double bond

Question 17

What is the simplest alkene?

Answer 17

Ethene C2H4

Question 18

What is the general formula for the alkenes?

Answer 18

CnH2n

Question 19

Name the alkenes and formulas for 1 to 8 carbons

Answer 19

Ethene C2H4 Propene C3H6 Butene C4H8 Pentene C5H10 Hexene C6H12 Heptene C7H14 Octene C8H16

Question 20

How are the carbon to carbon bonds in cycloalkanes?

Answer 20

All single

Question 21

What are isomers?

Answer 21

Isomers are substances with the same molecular formula but different structural formula eg cycloalkanes and alkenes

Question 22

What is the general formula for cycloalkanes?

Answer 22

CnH2n

Question 23

What does saturated mean?

Answer 23

All bonds are single

Question 24

How do you test for unsaturation?

Answer 24

To test if a hydrocarbon has double bonds we use bromine water. When bromine water is shaken with an unsaturated hydrocarbon the brown colour disappears

Question 25

What is crude oil?

Answer 25

Crude oil is a mixture of many hydrocarbon molecules

Question 26

What is distillation?

Answer 26

Distillation is two processes: evaporation followed by condensation

Question 27

What are the fractions when crude oil is distilled?

Answer 27

Fuel gases C1-C4 Petrol C8 Paraffin - jet fuel Diesel C16 - lorries and buses Bitumen

Question 28

As you go down the fractions what happens?

Answer 28

Molecular size increases Boiling point increases Viscosity increases Ignition temperature increases

Question 29

What process breaks down large molecules into smaller molecules?

Answer 29

Thermal cracking

Question 30

What is thermal cracking?

Answer 30

Breaking bonds to convert large molecules into smaller ones

Question 31

What is the shape of this?

Answer 31

Tetrahedral

Question 32

What is the shape of ammonia?

Answer 32

Pyramidal