Transition metals

Question 1

What happens when NH3 is added dropwise to Cu2+ (aq)?

Answer 1

Blue ppt Cu(OH)2 forms

Question 2

What happens when CuSO4 . 5H2O is dissolved in water?

Answer 2

Blue [Cu(H2O)6]2+ (aq) forms

Question 3

What happens when excess NH3 is added to Cu2+ (aq)

Answer 3

Dark blue [Cu(NH3)4(H2O)2]2+ forms

Question 4

What happens when excess HCl is added to Cu2+(aq)?

Answer 4

Yellow [CuCl4]2- forms

Question 5

What happens when Cu2+ is reduced with I–?

Answer 5

White CuI2 ppt forms and solution turns brown due to dissolved I2

Question 6

What happens when Cu+ is disproportionated in the presence of SO4-?

Answer 6

Brown solid Cu and blue solution CuSO4 form
Red solid CuO becomes brown solid

Question 7

What happens when CoCl2.6H2O(s) is added to
water and excess HCl?

Answer 7

Blue CoCl42- solution forms

Question 8

What happens when from KCr(SO4)2.12H2O(s) is dissolved in water?

Answer 8

Pale purple [Cr(H2O)6]3+ forms

Question 9

What happens when you add NH3 dropwise to Cr 3+(aq)?

Answer 9

Dark geen ppt of Cr(OH)3(s) forms

Question 10

What happens when you add excess NH3 to Cr 2+(aq)?

Answer 10

A purple [Cr(NH3)6]3+ solution forms

Question 11

What happens when you add excess OH– to Cr(OH)3
(s)

Answer 11

A solution with dark green [Cr(OH)6 forms

Question 12

What is the colour of K2CrO7 dissolved in acid?

Answer 12

Orange

Question 13

What happens when you oxidize Cr3+ with
hot alkaline H2O2

Answer 13

Yellow CrO42- forms

Question 14

What happens when you dissolve MnSO4.4H2O(s) crystals?

Answer 14

A pale pink solution of [Mn(H2O)6]2+ forms

Question 15

What happens when you add NaOH dropwise to Mn2+(aq)

Answer 15

A pale brown precipitate of Mn(OH)2(s) forms

Question 16

What happens when you dissolve crystals of FeSO4.7H2O(s) in water

Answer 16

A pale green solution of [Fe(H2O)6]2+ forms

Question 17

What happens when you add NaOH dropwise to Fe2+(aq)

Answer 17

A dark green precipitate of Fe(OH)2(s) forms

Question 18

What happens when you dissolve FeCl3.6H2O(s) in water

Answer 18

A yellow solution of [Fe(H2O)6]3+ forms

Question 19

What happens when you add NaOH dropwise to Fe3+(aq)?

Answer 19

Orange brown precipitate of Fe(OH)3(s) forms

Question 20

What is the colour change and equation in a permanganate titration to determine concentration of Fe2+

Answer 20

MnO4- + 5Fe2+ + 8H+ → 5Fe3+ + Mn2+ + 4H2O
Colour change purple (MnO4–) to pale pink (Mn2+)
(in titrations, so dilute that it is
practically colourless)

Question 21

What is the colour/ligand when Cr3+ is dissolved in aqueous solution

Answer 21

[Cr(H20)6]3+, dark green

Question 22

What is the colour/ligand when Cr2+ is dissolved in aqueous solution