Ligand Sub & Interconversions

Question 1

What is the colour of Cu2+ (aq) solution?

Answer 1

Blue

Question 2

What is the precipitate formed when NaOH is added to Cu2+ (aq)?

Answer 2

Blue precipitate

Question 3

What is the ionic equation for the precipitation reaction of Cu2+ (aq) with NaOH (aq)?

Answer 3

Cu2+ (aq) + 2OH- (aq) 🡪 Cu(OH)2 (s)

Question 4

What is the observation when NH3 (aq) is added in excess to Cu2+ (aq)?

Answer 4

Dark blue solution

Question 5

What is the ionic equation for the reaction when the precipitate of Cu(OH)2 dissolves in excess NH3 (aq)? Use complex ion formulas.

Answer 5

[Cu(H2O)6]2+ (aq) + 4NH3 (aq) 🡪 [Cu(NH3)4(H2O)2]2+(aq) + 4H2O (l)

Question 6

Ionic equation for the reaction when the precipitate of [Cu(H20)6]2+ dissolves in excess HCl. (Use complex ion formulas.

Answer 6

[Cu(H2O)6]2+ (aq) + 4Cl- (aq) 🡪 [CuCl4]2- (aq) + 6H2O (l)

Question 7

What is the color of Fe2+ (aq) solution?

Answer 7

Pale green

Question 8

What precipitate is formed when NaOH is added to Fe2+ (aq)?

Answer 8

Green precipitate

Question 9

What is the ionic equation for the precipitation reaction of Fe2+ (aq) with NaOH (aq)?

Answer 9

Fe2+ (aq) + 2OH- (aq) 🡪 Fe(OH)2 (s)

Question 10

What is the color of Fe3+ (aq) solution?

Answer 10

Yellow

Question 11

What colour precipitate is formed when NaOH is added to Fe3+ (aq)?

Answer 11

Rusty-brown precipitate

Question 12

What is the ionic equation for the precipitation reaction of Fe3+ (aq) with NaOH (aq)?

Answer 12

Fe3+ (aq) + 3OH- (aq) 🡪 Fe(OH)3 (s)

Question 13

What is the color of Mn2+ (aq) solution?

Answer 13

Pale Pink

Question 14

What colour precipitate is formed when NaOH is added to Mn2+ (aq)?

Answer 14

Light brown precipitate

Question 15

What is the ionic equation for the precipitation reaction of Mn2+ (aq) with NaOH (aq)?

Answer 15

Mn2+ (aq) + 2OH- (aq) 🡪 Mn(OH)2 (s)

Question 16

What is the color of Cr3+ (aq) solution?

Answer 16

Violet

Question 17

What colour precipitate is formed when NaOH is added to Cr3+ (aq)?

Answer 17

Grey-green precipitate

Question 18

What is the ionic equation for the precipitation reaction of Cr3+ (aq) with NaOH (aq)?

Answer 18

Cr3+ (aq) + 3OH- (aq) 🡪 Cr(OH)3 (s)

Question 19

Equation for when Cr(OH)3 (s) reacts with excess NaOH (aq)? (this is the only precipitate that does)

Answer 19

Cr(OH)3 (s) + 3OH- 🡪 [Cr(OH)6]3-(aq)

Question 20

What is the colour of the solution formed from dissolving [Cr(OH)6]3- (aq) in excess NH3?

Answer 20

Purple solution

Question 21

What is the ionic equation for the reaction when the precipitate of [Cr(OH)6]3+ (aq) dissolves in excess NH3 (aq)? Use complex ion formulas.

Answer 21

[Cr(H2O)6]3+(aq) + 6NH3(aq) 🡪
[Cr(NH3)6]3+(aq) + 6H2O(l)

Question 22

What is the observation when Fe2+, Fe3+, and Mn2+ react with excess NH3 (aq)?

Answer 22

No further reaction occurs

Question 23

What is the oxidation reaction of Fe2+ to Fe3+ using H+/MnO4-?

Answer 23

Fe2+ 🡪 Fe3+ + e-

Question 24

What is the reduction reaction of MnO4- using Fe2+?

Answer 24

MnO4- + 8H+ + 5e- 🡪 Mn2+ + 4H2O

Question 25

What is the overall redox reaction for the oxidation of Fe2+ by MnO4-?

Answer 25

MnO4- + 8H+ + 5Fe2+ 🡪 Mn2+ + 5Fe3+ + 4H2O

Question 26

What is the observation during the oxidation of Fe2+ to Fe3+ with MnO4-?

Answer 26

Purple (MnO4-) 🡪 Colourless

Question 27

Reduction of Fe3+ and Fe2+ using I- from KI: oxidation equation

Answer 27

Fe3+ + e- 🡪 Fe2+

Question 28

Reduction of Fe3+ and Fe2+ using I- from KI: reduction equation

Answer 28

2I- 🡪 I2 + 2e

Question 29

What is the overall redox reaction for the reduction of Fe3+ using I- from KI?

Answer 29

2Fe3+ + 2I- 🡪 2Fe2+ + I2

Question 30

What is the observation during the reduction of Fe3+ to Fe2+ using I-?

Answer 30

Colourless 🡪 Brown (I2)

Question 31

Reduction of Cr2O72- to Cr3+ using H+/Zn (this is to convert 6+ ox state to 3+): oxidation equation

Answer 31

Zn 🡪 Zn2+ + 2e-

Question 32

Reduction of Cr2O72- to Cr3+ using H+/Zn (this is to convert 6+ ox state to 3+): reduction equation

Answer 32

Cr2O72- + 14H+ + 6e- 🡪 2Cr3+ + 7H2O

Question 33

Reduction of Cr2O72- to Cr3+ using H+/Zn (this is to convert 6+ ox state to 3+): overall redox equation

Answer 33

Cr2O72- + 14H+ + 3Zn 🡪 2Cr3+ + 3Zn2+ + 7H2O

Question 34

What is the observation when Cr2O72- is reduced to Cr3+?

Answer 34

Orange (Cr2O72-) 🡪 Green (Cr3+)

Question 35

In presence of excess Zn... Further reduction occurs of Cr3+ to Cr2+: reduction equation

Answer 35

Cr3+ + e- 🡪 Cr2+

Question 36

In presence of excess Zn... Further reduction occurs of Cr3+ to Cr2+: oxidation equation

Answer 36

Zn 🡪 Zn2+ + 2e-

Question 37

What is the overall redox reaction for the further reduction of Cr3+ to Cr2+ using Zn?

Answer 37

2Cr3+ + Zn 🡪 2Cr2+ + Zn2+

Question 38

What is the observation during the further reduction of Cr3+ to Cr2+?

Answer 38

Green (Cr3+) 🡪 Blue (Cr2+)

Question 39

Oxidation of Cr3+ to CrO42– using OH-/H2O2: oxidation reaction

Answer 39

Cr3+ + 8OH- 🡪 CrO42- + 4H2O + 3e-

Question 40

Oxidation of Cr3+ to CrO42– using OH-/H2O2: reduction reaction

Answer 40

H2O2 + 2e- 🡪 2OH-

Question 41

What is the overall redox reaction for the oxidation of Cr3+ to CrO42- using OH-/H2O2?

Answer 41

3H2O2 + 2Cr3+ + 10OH- 🡪 2CrO42- + 8H2O

Question 42

What is the observation during the oxidation of Cr3+ to CrO42-?

Answer 42

Green (Cr3+) 🡪 Yellow (CrO42-)

Question 43

What is the overall redox reaction for the reduction of Cu2+ to Cu+?

Answer 43

2Cu2+ (aq) + 4I- (aq) 🡪 2CuI (s) + I2 (s)

Question 44

What is the observation during the reduction of Cu2+ to Cu+?

Answer 44

Blue (Cu2+) 🡪 White precipitate

Question 45

What is the equation for the disproportionation of Cu+?

Answer 45

2Cu2O (s) + H2SO4 (aq) 🡪 Cu (s) + CuSO4 + H2O

Question 46

What is the oxidation state change for Cu in the disproportionation reaction?

Answer 46

+1 to +2 and +1 to 0