O = Alkanes, alkenes, alcohols, cracking and crude oil

Question 1

State the method used to crack crude oil

Answer 1

Fractional distillation

Question 2

Why does crude oil go through cracking?

Answer 2

To break long chains of useless hydrocarbons into smaller useful hydrocarbons

Question 3

• Name the products of the fractional distillation of crude oil going from the lowest number of carbons.
• State the approximate temperatures the fractions are condensed at
• State the number of carbons within each fraction

Answer 3

• Refinery gases (C1-C4) = 25 degrees C
• Gasoline (petrol) (C6-C8) = 40 degrees C
• Naphtha (C6-C8) = 100 degrees C
• Kerosene (Paraffin) (C11-C15) = 190 degrees C
• Diesel oil (C16-C20) = 250 degrees C
• Fuel oil (C20-C30) = 330 degrees C
• Bitumen (C50+) = 350 degrees C

Question 4

Use of:
1-Refinery gases
2-Gasoline
3-Naphtha
4-Kerosene (Paraffin)
5-Diesel oil
6-Fuel oil
7-Bitumen

Answer 4

1-Bottled gas
2-Fuel for cars
3-Making chemicals
4-Aircraft oil
5-Fuel for cars e.g. lorries and buses
6-Fuel for ships, ferries, power stations
7-Roads and roof construction

Question 5

For hydrocarbons with a low boiling point and a high boiling point - Crude oil

• Volatility
• Ignition
• Ability to flow (Viscosity)

Answer 5

LOW BOILING POINT:

• Very volatile
• Ignites easily
• Flows easily

HIGH BOILING POINT:

• Not very volatile
• Doesn’t ignite easily
• Doesn’t flow easily

Question 6

General formula for:

1-Alkanes
2-Alkenes
3-Alcohols (and the functional group)

Answer 6

1-CnH2n+2

2-CnH2n

3-CnH2n+1OH
Functional group = OH

Question 7

Describe an experiment to explain catalytic cracking

Answer 7

Catalyst = normally silicon dioxide or porcelain chips which contain Al2O3

1-Heat a boiling tube that contains mineral wool soaked in one end of the the boiling tube. The catalyst is placed in the toiling tube but it doesn’t touch the mineral wool.

2-The gas released is collected over water.

3-You always make ethene along with others.

Question 8

Test for a C=C bond?

Answer 8

Use aqueous bromine water which is orange. It will turn colourless if there is a C=C bond present

Question 9

What type of reaction are these and what are the products of the reactions:

1-Bromination
(Mention haloalkanes)

2-Hydrogenation

3-Hydration

Answer 9

1-Addition of Br2 molecule. Add a Br2 molecule to the alkene to produce a dibromoalkane.
Halogen molecule + Alkene –> Haloalkane

2-Adding hydrogen to an alkene to make an alkane

3-Adding water to an alkene to make an alcohol

Question 10

Conditions for hydrogenation

Answer 10

Catalyst: Nickel
Temperature: 200 degrees C
Pressure: 200 atm

Question 11

Conditions for hydration

Answer 11

Catalyst: Phosphoric acid
Temperature: 300 degrees C
Pressure: 60 atm

Question 12

Equation for:

1-Complete combustion of alkanes?

2-Incomplete combustion of alkanes?

Answer 12

1-ALKANE + O2 –> CO2 + H2O + heat

2-ALKANE +O2 –> CO + H2O + heat

Question 13

Alcohols will undergo ____ when in the presence of which 2 catalysts?

Answer 13

Oxidation

Catalysts: Potassium dichromate and concentrated sulphuric acid

Question 14

2 ways of which Ethanol is formed?

State the conditions and describe each method.
Pros/cons

Answer 14

1-FERMENTATION

• Uses corn, sugar cane, rice (renewable)
• 30-40 degrees C
• Continuous process
• Slow reaction
• Low percentage yield/impure = 15%
• Produces 15% of CO2 for every 15% of ethanol produced
• Cheap

1-HYDRATION OF ETHENE

• Crude oil (non renewable)
• 300 degrees C and 60 atm
• Batch process
• Fast reaction
• High percentage yield/pure = 99%
• Expensive