Testing for cations Flashcards
1
Q
Testing for Cr 3+
A
NaOH - Green precipitate, dissolves in excess
NH3 - Grey-green precipitate, excess has no effect
2
Q
Testing for Cu 2+
A
NaOH - Pale blue precipitate, excess has no effect
NH3 - Pale blue precipitate, dissolves in excess, deep blue solution
3
Q
Testing for Ca 2+
A
NaOH - White precipitate, excess has no effect
NH3 - Very slight precipitate or none
4
Q
Testing for Al 3+
A
NaOH - White precipitate, dissolves in excess, gives colourless solution
NH3 - White precipitate, excess has no effect
5
Q
Testing for Fe 2+
A
EITHER NaOH/NH3 –> pale green precipitate
6
Q
Testing for Fe 3+
A
EITHER NaOH/NH£ –> red-brown precipitate
7
Q
Testing for Zn 2+
A
White precipitate, dissolves in excess of both NaOH and NH3
8
Q
Testing for NH4+
A
Add NaOH and heat, NH3 given off (turns litmus paper blue)
