1 Water

To flourish on the Earth, human, animal and plant life require a constant source of clean water. In many countries around the world new chemical technology is now needed to ensure economical and sustainable water management. As the population increases, industries develop and the understanding of the health implications of pollutants grows. Pollution is defined as the introduction into the environment (water, air or land) of contaminants, the quantities, characteristics and duration of which are likely to be injurious to human, animal or plant life.

The following questions about water quality arise for chemists:

• What chemicals are dissolved in water, such as anions, cations and organic compounds?
• What levels are considered as safe?
• What levels lead to pollution?
• How are unwanted chemicals and microorganisms removed?

In the following sections, by taking water purification as an example, you will see a number of important examples of where main-Group chemistry is important to our everyday lives. Here, several important anions and cations found in water will be considered. Additionally you will explore some chemistry associated with the nitrogen cycle, phosphororus, aluminium and thallium.