C2

• Temperature 450 C
• Pressure of 200 atmospheres
• Catalyst of iron

A low temperature increases the yield but the reaction is too slow.

A high pressure increases the yield but becomes more expensive as the yield increases as specialised equiptment is required.

A catalyst increases the rate of reaction but doesnt change the percentage yield.

It is not neccessary for a very high percentge yield as the reaction is reversable so no reactants are wasted. 

Eutrophication is when the overuse of fertilisers changes the ecosystem in lakes, rivers and streams.

1. Fertilisers may be washed into lakes and rivers (run-off). Tis increases the levels of nitrates and phosphates in the water and more algae grow.

2. The algal bloom blocks off sunlight to other plants, causing them to die and rot.

3. Aerobic bacteria feed on the dead organisms and increase in number. The quickly use up the oxygen until nearly all is removed. There isn enough oxygen left to support the larger organisms (fish) so they suffocate.