Chromium Cr Flashcards
(12 cards)
1
Q
what colour is [Cr(H2O)6] 3+ ?
A
pale purple (due to impurities is is common to appear green)
2
Q
what colour is Cr(OH)3 ?
A
dark green precipitate
3
Q
what colour is [Cr(NH3)6] 3+ ?
A
purple
4
Q
what colour is [Cr(OH)6] 3- ?
A
dark green
5
Q
what colour is Cr2O7 2- ?
A
orange
6
Q
what colour is CrO4 2- ?
A
yellow
7
Q
what forms [Cr(H2O)6] 3+ ?
A
KCr(SO4)2 • 12H2O (s)
8
Q
what is formed when NH3 is added drop wise to Cr 3+ ?
A
Cr(OH)3
9
Q
what is formed when excess NH3 is added to Cr 2+?
A
[Cr(NH3)6] 3+
10
Q
what is formed when excess OH is added to Cr(OH)3 ?
A
[Cr(OH)6] 3-
11
Q
what is Cr2O7 2- formed from?
A
K2Cr2O7 in 1 moldm H2SO4
12
Q
how is CrO4 2- formed?
A
oxidation of Cr 3+ with hot alkaline H2O2
