Test yourself using active recall!
Click on the arrows to cycle through the flashcards. For each ion or gas, describe the test to be carried out and the expected observations.
Practical Skills - Preliminary Observations
Test for cations
Some metal ions form precipitates with dilute sodium hydroxide and aqueous ammonia. We can make use of this chemical property as a qualitative test for unknown metal ions in solution.
We are interested to find out the following things about an unknown metal cation using this test:
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Does a precipitate form? If so, what colour is it?
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Does the precipitate dissolve in excess?
Test for anions
Watch this video to learn about the different tests for anions.
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Role of dilute nitric acid
What is the role of dilute nitric acid?
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Is the order of adding dilute nitric acid important?
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Test for gases
How to test for various gases using simple techniques.
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Note: It is important to ensure that when the litmus paper is used, it does not touch the walls of the test tube to prevent contamination resulting in false positives.
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Flame Test (Not in Syllabus)
Flame tests are used to identify the presence of a relatively small number of metal ions in a compound. Not all metal ions give flame colours.
Testing for water
Learn the basics about how to test water? what methods and techniques are use to test water? and why is water tested? Find out more in this video!