Fuels

Question 1

What are hydrocarbons

Answer 1

Compounds made up of hydrogen and carbon atoms ONLY

Question 2

What is crude oil

Answer 2

A complex mixture of hydrocarbons

Question 3

What does finite mean

Answer 3

Will run out/deplete

Question 4

What is fractional distillation

Answer 4

The separation of crude oil into into simpler, more useful
mixtures

Question 5

Explain the steps of fractional distillation in 3 steps

Answer 5

1. heated crude oil enters a tall fractionating column
   (which is hot at the bottom and gets cooler towards the top)
2. vapours from the oil rise up the column
3. condense when they get cool enough
4. liquids are let out at different heights

Question 6

List the 6 fractions that crude oil can be split into in order from highest to lowest

Answer 6

1. Gases
2. Petrol
3. Kerosene
4. Diesel oil
5. Fuel oil
6. Bitumen

Question 7

What are Gases used for?

Answer 7

Domestic home cooking

Question 8

What is Petrol used for?

Answer 8

Fuel for cars

Question 9

What is Kerosene used for?

Answer 9

Fuel for aircraft

Question 10

What is Diesel used for?

Answer 10

For some cars and trains

Question 11

What is Fuel oil used for?

Answer 11

For large ships and power stations

Question 12

What is Bitumen used for?

Answer 12

For fixing roofs and roads

Question 13

Describe how small molecules behave?

Answer 13

1. Low boiling point
2. Very volatile (ability to evapourate)
3. Low viscosity (thickness)
4. Ignites easily

Question 14

Describe how large molecules behave?

Answer 14

1. High boiling point
2. Not very volatile
3. High viscosity
4. Doesn’t ignite easily

Question 15

What is the homologous series?

Answer 15

a group of chemicals which have similar chemical properties

Question 16

What is the general formula for the homologous series?

Answer 16

Cn H2n+2

Question 17

Describe the complete combustion of hydrocarbons

Answer 17

CO2 and H2O are produced
Energy is given out (exothermic)

Question 18

Describe the incomplete combustion of hydrocarbons

Answer 18

Carbon (soot) and CO (carbon monoxide) are produced

Question 19

How does carbon monoxide act as a poisonous gas

Answer 19

it’s a colourless, odourless gas that binds to haemoglobin preventing oxygen to be carried around

Question 20

How impurities in some hydrocarbon fuels result in the production of sulfur dioxide

Answer 20

sulphur compounds found in hydrocarbon impurities when oxidised become sulphur dioxide

Question 21

Why is sulphur dioxide bad for the environment

Answer 21

Can dissolve in rainwater causing acid rain

Question 22

What 3 things does acid rain do

Answer 22

1. Destroy limewater monuments
2. Alter the pH of lakes killing animals
3. Reduce the growth/ kill off crops

Question 23

How is nitrogen dioxide formed

Answer 23

Nitrogen monoxide from exhaust pipes combines with oxygen to become nitrogen dioxide

Question 24

Advantages of replacing petrol with hydrogen

Answer 24

1. Isn’t a finite resource
2. only produces water

Question 25

Disadvantages of replacing petrol with hydrogen

Answer 25

1. Expensive
2. Difficult to store and transport hydrogen
3. Dangerous - can be explosive

Question 26

What is cracking

Answer 26

when larger hydrocarbon molecules are broken down into smaller, more useful hydrocarbon molecules

Question 27

What are the two types of cracking

Answer 27

Thermal Cracking
Catalytic Cracking

Question 28

Describe thermal cracking

Answer 28

1. Crude oil is heated to high temperatures (around 600-700°C) in the absence of oxygen
2. Breaks longer chains into shorter chains

Question 29

Describe catalytic cracking

Answer 29

1. Zeolite catalyst reduces the activation energy
2. Crude oil is heated to (around 450-550°C)
3. Higher yield of desired products produced