Tests for Cations
- Metal cations in aqueous solution can be identified by the colour of the precipitate they form on addition of sodium hydroxide and ammonia
- If only a small amount of NaOH is used then normally the metal hydroxide precipitates
Analysing results
- The table below contains the results for each of the cations included in the syllabus
- If a precipitate is formed from NaOH then the hydroxide is insoluble in water
Testing for Cations Table
Exam Tip
Sometimes you may not see much of a precipitate because the cation you are testing is present is very small amounts. However, every a slight cloudiness or colour change can indicate a positive test result.
