Precipitation Reactions Flashcards
1
Q
Cu2+
A
Pale blue solution
2
Q
Cu(OH)2
A
Blue precipitate
3
Q
Fe2+
A
Pale green solution
4
Q
Fe(OH)2
A
Green precipitate
5
Q
What colour does the green Fe(OH)2 precipitate turn after standing in air?
A
Brown at its surface. Iron (II) is oxidised to iron (III). Fe(OH)2 -> Fe(OH)3
6
Q
Fe3+
A
Pale yellow solution
7
Q
Fe(OH)3
A
Orange-brown precipitate
8
Q
Mn2+
A
Pale pink solution
9
Q
Mn(OH)2
A
Light brown precipitate
10
Q
Cr3+
A
Violet solution
11
Q
Cr(OH)3
A
Green precipitate
12
Q
Which hydroxides that you have studied do not dissolve in excess NaOH?
A
Cu2+, Fe2+, Fe3+, Mn2+
13
Q
Which hydroxide does dissolve in excess NaOH?
A
Cr3+
Cr3+ -> Cr(OH)3 -> [Cr(OH)6]3-
Violet solution -> Green precipitate -> Dark green solution
14
Q
Which hydroxides do not dissolve in excess NH3?
A
Fe2+, Fe3+, Mn2+
15
Q
Which hydroxides do dissolve in excess NH3?
A
Cu2+, Cr3+
