AS Chemistry cation identification tests a visual guide
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Designed by Samuel Mill
description
AS Chemistry cation identification tests a visual guide. Designed by Samuel Millar. KEY. suspected aqueous cation (colour indicated). precipitate. solution. smoke. reagent solution:. {. NaOH (aq) sodium hydroxide solution NH 3 (aq) ammonium hydroxide solution - PowerPoint PPT Presentation
Transcript of AS Chemistry cation identification tests a visual guide
Designed by Samuel Millar
KEYsuspected aqueous
cation(colour indicated)
{NaOH (aq) sodium hydroxide solutionNH3 (aq) ammonium hydroxide solutionKSCN(aq) potassium thiocyanate solutionK2CrO4 (aq) potassium chromate solution
reagentsolution:
precipitate
solution
smoke
NH3 (aq)(add dropwise)
Cu2+(aq)
pale blue pptsoluble in excess:
deep blue soln(complex ion solution)
pale blue pptinsoluble in excess
COPPER (II)
NaOH (aq)
Cu2+(aq)
NH3 (aq)or
NaOH (aq)
Fe3+(aq)
rust-brown pptinsoluble in excess
blood red soln(complex ion solution)
IRON (III)
KSCN (aq)
Fe3+(aq)
NH3 (aq)or
NaOH (aq)
Fe2+(aq)
dirty green pptinsoluble in excess
IRON (II)
KCrO4 (aq)
Ba2+(aq)
yellow pptsoluble in hydrochloric acid:
yellow soln
BARIUM (II)
NaOH(aq)
NH4+
(aq)
pungent colourless gas evolvedreacts with hydrogen chloride vapour:
white smoke
AMMONIUM
HEAT
ALUMINIUM (III), ZINC (II), MAGNESIUM (II)
These cations all produce white precipitates with NaOH and NH3 solutions. The precipitates have the following solubilities in excess:
NaOH(aq)
NH3(aq)
Al3+
(aq)Zn2+
(aq)Mg2+
(aq)
soluble: colourless soln
(ppt amphoteric)
soluble: colourless soln
(ppt amphoteric)
soluble: colourless soln
(complex ion soln)
insoluble insoluble
insoluble
FLAME TESTSCation Flame colourLi+ Crimson-redNa+ Yellow/orangeK+ Lilac/pink through blue glassCa2+ Brick redSr2+ RedBa2+ GreenCu2+ Blue-greenBurning glass Orange!
