Alkanes

Question 1

What is a hydrocarbon?

Answer 1

A hydrocarbon is a molecule only made of oxygen and hydrogen

Question 2

Are alkanes hydrocarbons?

Answer 2

Yes

Question 3

Which type of bonds do alkanes have?

Answer 3

Singular bonds

Question 4

First 4 alkanes

Answer 4

Methane, Ethane, Propane, Butane (Monkeys Eat Peanut Butter)

Question 5

Complete combustion equation for hydrocarbons

Answer 5

Hydrocarbon + Oxygen -> Carbon dioxide + Water

Question 6

When does complete combustion take place?

Answer 6

Only when there is enough oxygen available

Question 7

What is the equation for the complete combustion of propane?

Answer 7

C3H8 + 5O2 -> 3CO2 + 4H2O

Question 8

Properties of alkanes

Answer 8

Boiling points increase as molecules get larger, smaller molecules are voletile and highly flammable (good fuels), larger molecules are viscous

Question 9

During a combustion reaction in alkanes, are the oxygen and hydrogen reduced or oxidised?

Answer 9

Oxidised

Question 10

Crude oil is mostly made up of hydrocarbons

Answer 10

True

Question 11

What process is used to seprate crude oil into different substances?

Answer 11

Fractional distillation

Question 12

What is ‘cracking’ used for?

Answer 12

To break down longer chains of hydrocarbons into shorter ones

Question 13

2 types of cracking

Answer 13

Catalytic cracking and steam cracking

Question 13

Explain catalytic cracking

Answer 13

• hydrocarbons are vaporised
• the hydrocarbon vapour is passed over powdered aluminium oxide (catalyst)
• the hydrocarbons split into shorter pieces as they come into contact with the catalyst

Question 14

Explain steam cracking

Answer 14

• hydrocarbons are vaporised
• the gas is mixed with steam and heated to a high temp
• the hydrocarbons split into shorter pieces

Question 15

Equation for cracking

Answer 15

Alkane -> Shorter alkane + Alkene

Question 16

How is an alkane different an alkene

Answer 16

An alkene has 1 double bond, alkanes only have singular bonds

Question 17

What is a homolgous series?

Answer 17

A group of similar compounds with similar properties

Question 18

What would you call an alkane?

Answer 18

‘Saturated’ as they only have singular bonds. Alkenes are ‘unsaturated’

Question 19

Are alkenes more reactive than alkanes?

Answer 19

Yes

Question 20

What will happen in a reaction between bromine and an alkene?

Answer 20

A solution of alkenes will decolourise orangey-brown bromine water (test for alkenes)

Question 21

How can alkenes make polymers?

Answer 21

The double bonds can break to form 2 or more bonds

Question 22

What type of reaction can alkenes undergo?

Answer 22

Addition reaction

Question 23

How does an addition reaction work?

Answer 23

Carbon double bond opens up and allows 2 other molecules to join

Question 24

Hydrogenation reaction

Answer 24

• At 150 celsius
• With nickle catalyst
• Reaction with hydrogen and alkene
• Produces alkane

Question 25

Halogenation reaction

Answer 25

• At room temp
• ## With any halogen and alkene

Question 26

Hydration reaction

Answer 26

• At 300 celsius
• Phosphoric acid catalyst
• 60 atmospheric pressure
• Produces an alcohol