Ligand Substitution And Precipitation

Question 1

Ligand substitution

Answer 1

Reversible reaction
Complex ion
One ligand replaces by another ligand

Question 2

[Cu(H2O)6]2+

+ excess NH3 (aq)

Answer 2

4 H2O replaces by 4 NH3
PALE BLUE > DARK BLUE
Both octahedral

Question 3

[Cu(H2O)6]2+

+ excess Cl- (aq)

Answer 3

HCl
6 H2O replaces by 4 Cl- (product 2-)
PALE BLUE > YELLOW
Octahedral > tetrahedral

Question 4

[Cr(H2O)6]3+

+ excess NH3

Answer 4

6 H2O replaces by 6 NH3
VIOLET > PURPLE
Octahedral > octahedral

Question 5

Haemoglobin + O2

Answer 5

Oxyhemoglobin

Deep red

Question 6

Haemoglobin + CO

Answer 6

Carboxyhaemoglin
DEEP PINK
Irreversible

Question 7

Precipitate reaction

Answer 7

Ions of two aq solutions > insoluble ionic solid (ppt)

OH)2 / (OH3

Question 8

Solutions providing OH-

Ppt formed

Answer 8

NaOH
NH3
(Metal hydroxides)

Question 9

Cu2+ +OH-

Answer 9

PALE BLUE aq > BLUE ppt

Question 10

Fe2+ +OH-

Answer 10

PALE GREEN aq > GREEN ppt

Brown surface - oxidised by air

Question 11

Fe3+ +OH-

Answer 11

PALE YELLOW aq > ORANGE BROWN ppt

Question 12

Mn2+ +OH-

Answer 12

PALE PINK aq > LIGHT BROWN ppt

Question 13

Cr3+ +OH-

Answer 13

VIOLET aq > GREEN ppt

Question 14

Excess Na OH

Do not

Answer 14

Cu2+
Fe2+
Fe3+
Mn2+

Question 15

Excess NaOH

Does dissolve

Answer 15

Cr3+ (aq)
VIOLET aq > GREEN ppt
GREEN ppt > DARK GREEN aq
FORMS LIGANDS

Question 16

Excess NH3

Doesn’t dissolve

Answer 16

Fe2+
Fe3+
Mn2+

Question 17

Excess NH3

Does dissolve

Answer 17

Cu2+
Cr3+
FORMS LIGANDS

Question 18

Excess NH3

Cr3+

Answer 18

VIOLET aq > GREEN ppt > PURPLE aq

Question 19

Excess NH3

Cu2+

Answer 19

PALE BLUE aq > BLUE ppt > DARK BLUE aq