Transition elements colours

Question 1

name the five transition elements that you need to know

Answer 1

Fe 2+
Fe 3+
Mn 2+
Cr 3+
Cu 2+

Question 2

colour change when Fe 2+ reacts with hydroxide

Answer 2

Fe(OH)2 - pale green to green

Question 3

colour change when Fe 3+ reacts with hydroxide

Answer 3

Fe(OH)3 - orange to brown

Question 4

colour change when Mn 2+ reacts with hydroxide

Answer 4

Mn(OH)2 - pale pink to pale brown

Question 5

colour change when Cr 3+ reacts with hydroxide

Answer 5

Cr(OH)3 - green to pale green

Question 6

colour change when Cu 2+ reacts with hydroxide

Answer 6

Cu(OH)2 - Blue to pale blue

Question 7

what happens when Fe(OH)2 oxidises

Answer 7

Fe(OH)2 -> Fe(OH)3
oxidises in the air
colour change - green to brown

Question 8

what happens when Mn(OH)2 oxidises

Answer 8

Pale brown colour darkens

Question 9

Cr3+ -> Cr(OH)3
reagents and colour change

Answer 9

Diluted OH- and Diluted NH3
green to grey green

Question 10

Cr(OH)3 -> [Cr(OH)6]3-
Reagents and colour change

Answer 10

Excess OH-
Grey green to dark green solution

Question 11

Cr(OH)3 reaction with concentrated NH3

Answer 11

[Cr(NH3)6]3+
grey green ppt to purple solution

Question 12

Cu(OH)2
reaction with excess OH-

Answer 12

No change/ reaction

Question 13

Cu+ reaction with [CuCl4]2-

Answer 13

Cu2+ -