Topic 8 Fuels And Earth Science

Question 1

How is crude oil separated?

Answer 1

By fractional distillation:the oil is heated unite most of it is turned to gas.And the gas enter the fractional column.
The longer hydrocarbons have higher boiling points so they turn to liquids and drain out of the column early on when near the bottom.
The shorter hydrocarbon have lower boiling points so will drain out of the column later on near to top of column where it is cooler

Question 2

What is a homologous series?

Answer 2

Family of molecules with same general formula and share different chemical properties.They physical properties vary the bigger the molecule the higher the boiling point.

Question 3

What determines the properties of hydrocarbons?

Answer 3

Boiling points:
Shorter hydrocarbon easy to ignite:because they have lower boiling points
Longer hydrocarbons hard to ignited:because the have higher boiling points

Viscosity:measure how easy substance flows(stronger force=higher viscosity)
Longer hydrocarbons-are thick so have higher viscosity
Shorter hydrocarbons-runnier so have low viscosity

Intermolecular forces:
Shorter the hydrocarbon the weaker the intermolecular forces so easy to break
Longer the hydrocarbon the stronger the intermolecular forces so harder to break

Question 4

What do incomplete combustion produce?

Answer 4

Toxic carbon monoxide and soot and if get in body can affect blood circulation leading to faint or death

Question 5

What does sulfur dioxide cause?

Answer 5

Acid rain:fossil fuels burn releasing CO2 and sulfur dioxide
When mixed with clouds it forms acid rain
Which causes lakes to be acidic and kill trees

Question 6

Pros and cons of hydrogen gas?

Answer 6

Pros:clean
Renewable

Cons: uses expensive engine
is rare source of energy

Question 7

What does cracking do?

Answer 7

Turns long saturated molecules into smaller unsaturated and Alkane molecules
Form of decomposition
A lot of longer molecules produced from fractional distillation are cracked into smaller ones to increase demand for petrol and diesel
Cracking involves breaking covalent bonds so catalyst is used to speed this up

Question 8

How did atmosphere evolve in phase1(volcanoes)?

Answer 8

1. earth surface was molten
2. eventually it cooled and formed thin crust but volcanoes kept erupting introducing gases from the earth
3. when thing settled down the early atmosphere was mostly CO2 there was vapor there and was little oxygen
4. the vapor condensed to form oceans

Question 9

How did green plants evolve phase 2.?

Answer 9

1. early CO2 dissolved in oceans
2. nitrogen was put in atmosphere by denitrifying bacteria
3. green plants evolved from the atmosphere and photosynthesis to remove CO2 and produce O2
4. leading to build up of oxygen

Question 10

How was did animals evolve in the atmosphere phase3?

Answer 10

1. Build up of oxygen killed off early organisms but allowed evolution of complex organisms that made use of oxygen
2. the oxygen also created the ozone layer which enabled the developement of of more organisms

Question 11

What affects the composition of the air?

Answer 11

Increase in human population causes more people to respire causing more CO2 also meant increase use of energy resources which led to increase of gases into the atmosphere

Question 12

How does the greenhouse effect keep earth warm?

Answer 12

Greeenhosue gases in atmosphere absorb heat radiated from the earth the greenhouse gases then release energy in all directions,This reduces heat radiated into space keeping earth warm

Question 13

What affect does increase in greenhouse gases have on climate change?

Answer 13

Increases temperature and CO2 levels in the atmosphere from energy used from humans known as global warming

Question 14

How do you prevent climate change?

Answer 14

Walking and cycling instead of transport this reduces carbon dioxide emissions
Use renewable energy