fuels and earth science

Question 1

What are hydrocarbons

Answer 1

Compounds that contain hydrogen and carbon only

Question 2

What is crude oil

Answer 2

• a complete mixture of hydrocarbons
• containing molecules in which carbon atoms are in chains or rings
• an important source of useful substances
• a finite resource

Question 3

How can you separate crude oil into simpler and more useful mixtures by fractional distillation

Answer 3

• The oil is heated until most of it has turned into a gas and the gases enter a fractionating column
• in the column there is a temperature gradient, the longer hydrocarbons have higher boiling points. They turn back into liquids and drain out of the column early on when they’re near the bottom. The shorter carbohydrates have lower boiling points. They tend to liquid and drain out much later on to the top of the column where it’s cooler.
• each fraction contains a mixture of hydrocarbons mostly alkalenes with similar boiling points

Question 4

What is the fraction, gas, used for?

Answer 4

Used in domestic heating and cooking

Question 5

What is the fraction, petrol, used for?

Answer 5

Fuel for cars

Question 6

What is the fraction, kerosene, used for?

Answer 6

Use as fuel for aircraft

Question 7

What is the fraction, diesel oil, used for?

Answer 7

used for fuel for some cars and trains

Question 8

What is the fraction, fuel oil, used for?

Answer 8

Used as fuel for large ships and in some power stations

Question 9

What is the fraction, bitumen, used for?

Answer 9

Used to surface roads and roofs

Question 10

How hydrocarbons in different fractions differ from each other regarding boiling points

Answer 10

• Big molecules have higher boiling points in small molecules do this because it takes a lot of energy and force of attraction to break the bonds

Question 11

How hydrocarbons in different fractions differ from each other regarding ease of ignition

Answer 11

Short hydrocarbons are easy to ignite because they have lower boiling points so tend to be gases at room temperature
- these gas molecules mixed with oxygen in the air to produce a gas mixture which burst into flames if it comes into contact with a spark
- longer hydrocarbons are usually liquid liquids at room temperature they have higher boiling points in a much harder to ignite

Question 12

How hydrocarbons in different fractions differ from each other regarding viscosity

Answer 12

• viscosity measures how easily a substance flows
• The stronger the force is between the hydrocarbon molecules the harder is for the liquid to flow
• longer hydrocarbons have a higher viscosity so they’re thick

Question 13

How hydrocarbons in different fractions differ from each other regarding number of carbon and hydrogen atoms their molecules contain

Answer 13

As it gets cooler, the number of carbons in the hydrocarbon in that fraction is lower
- in gases, there may be -3 carbons in the hydrocarbon
- in between there is approximately 70+ number of carbons in the hydrocarbons

Question 14

What are hydrocarbons in different fractions members of

Answer 14

Alkane homologous series

Question 15

What is the homologous series as a series of compounds which:

Answer 15

• have the same general formula
• differ by CH2 in molecular formulae from neighbouring compounds
• show a gradual variation in physical properties, as exemplified by their boiling points
• have similar chemical properties

Question 16

What is produced and given out in a complete combustion of hydrocarbon fuels as a reaction

Answer 16

Carbon dioxide and water is given out
Energy is given out

Question 17

What is incomplete combustion

Answer 17

Occurs when a hydrocarbon burns in a limited supply of oxygen

Question 18

What happens during incomplete combustion

Answer 18

Tiny particles of carbon can be released into the atmosphere
When they fall back to the ground, they deposit themselves as soot

Question 19

Why is carbon monoxide a toxic gas?

Answer 19

Carbon monoxide can combine with red blood cells and stop your blood from carrying oxygen around the body
- a lack of oxygen in the blood supply to the brain and need to fainting, a coma or even death

Question 20

What can impurities in hydrocarbon fuels result in

Answer 20

Sulfur dioxide

Question 21

How can sulphur dioxide cause acid rain?

Answer 21

When sulphur dioxide mixes with cloud clouds, it forms sulphuric acid this then falls as acid rain

Question 22

How do oxygen and nitrogen produce pollutants when reacted together at high temperatures?

Answer 22

Nitrogen oxide are created from a reaction between the nitrogen and oxygen in the air, caused by the energy released by combustion reaction
Nitrogen oxide can contribute to acid rain and that ground level can cause photochemical smog

Question 23

What are advantages of using hydrogen rather than petrol as a fuel in cars?

Answer 23

• It’s a very clean fuel
• only waste product is water
• renewable resource

Question 24

What are disadvantages of using hydrogen rather than petrol as fuel in cars?

Answer 24

• need a special, expensive engine
• uses energy from another source
• hydrogen is hard to store and not widely available

Question 25

What is kerosene, petrol, and diesel oil?

Answer 25

Non-renewable fossil fuels obtained from crude oil

Question 26

What is methane?

Answer 26

Non-renewable fossil fuel found in natural gas

Question 27

How does cracking happen?

Answer 27

- Breaks down larger, saturated hydrocarbon molecules into smaller, more useful ones some of which are unsaturated - when one substance breaks down into at least two new ones when you heat it- this means breaking strong covalent bonds you need lots of energy

Question 28

Why is cracking necessary?

Answer 28

It produces lots of alkenemolecules which can be used to make polymers

Question 29

What did the gases produced by volcanic activity form?

Answer 29

The earths early atmosphere

Question 30

What does the earths early atmosphere was thought to contain?

Answer 30

- Little or no oxygen - A large amount of carbon dioxide - Water vapour - Small amount of other gases

Question 31

How does condensation of water vapour form oceans?

Answer 31

The Earth called down and this caused water vapour to condense and fall to make oceans

Question 32

How did the amount of carbon dioxide in the atmosphere decrease when carbon dioxide dissolved as the oceans formed?

Answer 32

Really fast

Question 33

How the growth of primitive plants used carbon dioxide and released oxygen by photosynthesis and consequently the amount of oxygen in the atmosphere gradually increased

Answer 33

The amount of oxygen in the air gradually built up and much of the carbon dioxide eventually got locked up in fossil fuels and sedimentary rocks

Question 34

Chemical test for oxygen

Answer 34

Check if the gas will relight a glowing splint

Question 35

What is the greenhouse effect?

Answer 35

Various gases in the atmosphere, including carbon dioxide, methane and water vapour, absorb heat radiated from the Earth, subsequently releasing energy which keeps the Earth warm

Question 36

As the years increase percentage of carbon dioxide in the atmosphere increases

Question 37

What is the composition of today’s atmosphere?

Answer 37

78% nitrogen and approximately 21% oxygen Small amounts of other gases, mainly carbon dioxide, noble gases and water vapour

Question 38

What are the potential effects on the climate of increased levels of carbon dioxide and methane generated by human activity, including burning fossil fuels and livestock farming?

Answer 38

Global warming is a type of climate changing causes other types of climate change it can cause severe flooding to the polar ice caps melting