Chemical tests

Analytical chemistry involves the identification of chemical substances using a variety of methods.

Although modern technology has enabled chemists to analyse and identify a huge range of substances very quickly and accurately some simple test tube reactions can still be quicker and cheaper to perform.


2.44 describe tests for these gases:
hydrogen, oxygen, carbon dioxide, ammonia, chlorine.
2.45 describe how to carry out a flame test
2.46 know the colours formed in flame tests for these cations:
Li+is red,Na+is yellow, K+ is lilac, Ca2+is orange-red, Cu2+is blue-green.
2.47 describe tests for these cations:
 NH4+ using sodium hydroxide solution and identifying the gas evolved, Cu2+, Fe2+and Fe3+using sodium hydroxide solution.
2.48 describe tests for these anions:
Cl, Brand Iusing acidified silver nitrate solution SO42– using acidified barium chloride solutionCO32–using hydrochloric acid and identifying the gas evolved.
2.49 describe a test for the presence of water using anhydrous copper(II) sulfate
2.50 describe a physical test to show whether a sample of water is pure

This video gives a good overview of the main trends in solubility of  the compounds which you will meet at GCSE. 

If you have not already done so you should learn the names and fomulae of the ions shown above and below: 

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The solubility table - you need to learn this.

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This table is important to learn  - so that you can use it to predict what will happen when two solutions are mixed. Some examples are 

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