Environmental Problems

Question 1

What is complete combustion?

Answer 1

When there is plenty of oxygen and all the fuel burns

Question 2

What is partial combustion? Results?

Answer 2

When there is not enough oxygen, and some of the fuel doesn’t burn

→ Under these conditions, solid particles (particulates) of soot (carbon) and unburnt fuel are released, along with carbon monoxide

Question 3

What is global warming?

Answer 3

A type of climate change and causes other types of climate change eg change in rainfall patterns

Question 4

Evidence for global dimming?

Answer 4

Scientiss found that some areas nearly 25% less sunlight has been reaching the surface compared to 50 years ago

Question 5

Cause of global dimming?

Answer 5

They THINK its caused by particles of soot and ash that are produced by fossil fuels being burnt

→ These particles reflect sunlight back into space, or they can help to produce more clouds that reflect the sunlight back into space

Question 6

New alternative fuels? Pro;s and cons?

Answer 6

• Ethanol

Can be produces from lpant material so is known as a biofuels. It is made by fermentation of plants and is used to power cars in some places. It’s often mixed with petrol to make better fuel

✓ The CO₂ released when its burnt was taken by the plant as it grew, so its ‘carbon neutral’ (the only other product is water)

✗ Engines need to be converted before they’ll work with Ethanol fuels. And ethanol fuel isn’t widely avaliable. There are worries that farmers may switch from growing food to growing crops to make ethanol - so food prices will rise

• Biodiesel

Another type of biofuel, it can be produces from vegetable oils such as rapeseed oil and soybean oil. Biodiesel can be mixed with ordinary diesel fuel and used to run a diesel engine

✓ ‘Carbon neutral’. Engines don’t need to be converted. It produces much less sulfur dioxide and ‘particulates’ than oridinary diesel or petrol

✗ We can;t make enough to completely replace diesel. It’s expensive to make. It could increase food prices

• Hydrogen gas

Can also be used to power vehicles. You get the hydrogen from the electolysis of water - theres plenty of water but it takes plenty of energy to split it up - this energy can come from a renewable source

✓ Hydrogen combines with oxygen in the air to form ust water - so its very clean

✗ You need a special, expensive engine and hydrogen isn’t widely avaliable. You still need to use energy from another source to make it. Its also hard to store