8300551
Description
Mind Map by Lily O'Brien, updated more than 1 year ago
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Created by Lily O'Brien
over 7 years ago
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C3 -Test for positive ions
- Some metals burn with a characteristic colour
- Lithium - crimson
- Sodium - yellow
- Potassium - lilac
- Calcium - red
- Barium - green
- To test a compound, dip a nichrome (clean) wire
loop into a sample of the compound and put it in
the clear blue part of the Bunsen flame. Make
sure it is clean by dipping it into hydrochloric
acid and rinsing it with distilled water.
- Lithium - crimson
- Some metal ions form a coloured precipitate with NaOH
- Many metal hydroxides are insoluable and precipitate out of
solution when formed. Some have a characteristic colour
- Add a few drops of sodium hydroxide solution to the solution of the mystery
compound. If you get a coloured compound you can tell which metal it was.
- Calcium - white (Ca2+ + 2OH- = Ca(0H)2
- Copper(II) - blue (Cu2+ + 2OH- = Cu(0H)2
- Iron(II) - green (Fe2+ + 2OH- = Fe0H)2
- Iron(III) - brown (Fe3+ + 3OH- = Fe(0H)3
- Aluminium - White at first then redissolves in excess NaOH to form a colourless solution. (Al3+ +
3OH- = Al(0H)3 then Al(OH)3+ OH- = Al(OH)4
- Magnesium - White (Mg2+ + 2OH- = Mg(0H)2)
- Many metal hydroxides are insoluable and precipitate out of
solution when formed. Some have a characteristic colour
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