Hydrocarbons

Question 1

A fuel is a substance which ….

Answer 1

Releases energy when burned.

Question 2

When hydrocarbons are burnt in oxygen they produce…

Answer 2

carbon dioxide and water

Question 3

If hydrocarbons burn with insufficient oxygen, what is produced?

Answer 3

Carbon monoxide and water

Question 4

Why is carbon monoxide poisonous?

Answer 4

CO combines with red blood cells reducing their capacity to carry oxygen.

Question 5

Some fuels contain sulfur. What other gas is produced when they are burned?

Answer 5

Sulphur dioxide

Question 6

When sulfur dioxide is released into the air it combines with moisture and oxygen to form……

Answer 6

Acid rain

Question 7

High temps in car engine can cause nitrogen and oxygen to combine to form….

Answer 7

Nitrogen oxides

Question 8

Nitrogen oxide and sulfur dioxide both contribute to ….

Answer 8

Acid rain

Question 9

Acid rain can cause what problems?

Answer 9

Lakes and streams become acidic and kill plants and fish

Releases ions into the soil which are poisonous to trees and destroys forests

Question 10

How many bonds does carbon form?

Answer 10

4

Question 11

How many bonds does hydrogen form?

Answer 11

1

Question 12

When a hydrocarbon only has single bonds the compounds are called…

Answer 12

Alkanes

Question 13

The first 5 members of the alkanes are

Answer 13

n= 1 Methane. Monkeys eat peeled bananas.  
n=2 Ethane.
n=3 Propane
n=4 Butane 
n=5 Pentane

Question 14

Alkanes are saturated hydrocarbons with single bonded carbon.
The general formula for alkanes is …..

Answer 14

C (n) H (2n+2)

Question 15

What is an Isomer?

Answer 15

Isomers are compounds which have the same molecular formula but different structural formula

Question 16

In combustion, alkanes burn in air to produce ….

Answer 16

CO2 carbon dioxide

H2O water

Question 17

Do hydrocarbons have ionic or covalent bonding?

Answer 17

Covalent

Question 18

Why don’t hydrocarbons take part in many chemical reactions?

Answer 18

Strong covalent bonds so difficult to break

Question 19

Hydrocarbons react with 2 halogens which are…

Answer 19

Bromine and chlorine (alkanes need uv light to react)

A Substitution reaction

Question 20

Definition of an alkene

Answer 20

• An alkene is a hydrocarbon that contains a double bond

- It is unsaturated as the double bond can split so the carbon can join with other atoms.

Question 21

Alkenes are unsaturated hydrocarbons. Does this make them more or less reactive than alkanes?

Answer 21

More reactive and so more useful

Question 22

What is the general formula for alkenes?

Answer 22

C n H 2n

Question 23

What is a hydrocarbon?

Answer 23

Molecules made up of hydrogen and carbon atoms only

Question 24

What does saturated mean?

Answer 24

The carbon atoms cannot bond with any more atoms

Question 25

What does unsaturated mean?

Answer 25

Unsaturated hydrocarbons can make more bonds.

The double bond splits and joins with other atoms. Like in alkenes.

Question 26

What colour change does bromine water have when you add an alkene?

Answer 26

Bromine after turns orange to colourless

Question 27

What three characteristics of the compounds in a homologous series have?

Answer 27

• Have same general formula
• Similar chemical properties
• Gradual change in physical properties

Question 28

2 conditions required for cracking are…

Answer 28

Heat and a catalyst
600 to 700 degs C
Silica or aluminium oxide catalyst