- Created by: Sam
- Created on: 05-04-12 13:19
Based on Edexcel Textbook
pg 82-83 Water, Water Everywhere
We need a safe water supply to survive. Analytical Chemists anaylse our water supplies in the UK to see what is in them. They use Qualitative measure to find what is present and Quantitative measures to find how much of each substence is present. Water is treated by screening and filtering some chemicals are added to the water for specific purposes for example chlorine is added to water to kill bacteria. Pollution can come from industries or from fertiliser run off. The Government sets standards for how much of each pollutant can be in the supply.
pg 84-85 Testing for Ions
Ions are atoms that have lost or gained electrons. Ionic compounds can be found dissolved in water. Usually made up of a metal and a non-metal. Metals usually form postive ions called cations by losing electrons. Non-metals usually form negative ions called anions by gaining electrons. To analyse what compound is present you need to do at least two tests to find each of the ions. There must be a test unique to each ion so that you can be sure of the result.
Metal ions produce different coloured flames so a flame test can be used to determin what metal ion is present. The coloured are produced because the atoms have different energy levels. Calcium is brick-red, Sodium is Yellow, Potassium is lilac and Copper is…