Year 10 Research Assignment
By Welton Chan
Year 10 Science
Explain the significance of ozone to life on Earth
Ozone is a gas that naturally occurs in the stratosphere. It acts as a shield and is able to absorb most of the Sun's harmful ultraviolet radiation before it reaches the Earth's surface. Harmful ultraviolet radiation can increase the likelihood of skin cancers and eye damage, and slow down photosynthesis. By having ozone, it protects living things from the harmful high-energy radiation from the Sun.
What have humans done to damage it?
Humans have damaged ozone by using Chlorofluorocarbons. Chlorofluorocarbons are greenhouse gases that destroy ozone. Chlorofluorocarbons are found in factories in developing countries and in some spray cans. Nitrogen oxides from jet aircraft engines when they burn fuels also speeds up ozone destruction. Moreover, hydrogen chloride from space shuttles taking off damages ozone.
Is the damage reversible?
The damage done to the ozone layer is reversible but it will take a lot of effort and international cooperation to repair it.
It is expected that ozone levels will return to normal by 2045.
Discuss the different methods used to extract metals from their ores and the advantages and disadvantages of each method
There are three basic ways of extracting metals from their ores. Pyrometallurgy is the treatment of metals and their ores by heat. Pyrometallurgy includes smelting and roasting. Smelting is a process of heating and melting ores and then separating the desirable molten metals from other elements. For less stable metals, a reducing agent such as carbon or carbon monoxide is used. For more stable metals, roasting is used. Roasting is the heating of ores in air.
At high temperatures, reactions are much faster than they are in slurries or in aqueous solutions.
In sulphide systems...