Complex Ions + Ligand Substitution Reactions

Question 1

What is copper sulphate solutions colour, formula and ligand?

Answer 1

Colour: blue solution
Formula: [Cu(H2O)6]2+
Ligand: H2O
Shape: octahedral

Question 2

What is iron (II) sulphate solutions colour, formula, shape and ligand?

Answer 2

Colour: pale green
Formula: [Fe(H2O)6]2+
Ligand: H2O
Shape: octahedral

Question 3

What is iron(III) sulphate solutions colour, formula and ligand?

Answer 3

Colour: yellow solution
Formula: [Fe(H2O)6]3+
Ligand: H2O
Shape: Octahedral

Question 4

What is the ionic equation, colour, and anion for iron (III) sulphate + sodium hydroxide ?

Answer 4

Ionic equation: Fe3+ (aq) + 3OH- (aq) => Fe(OH)3 (s)
Colour: foxy brown ppt
Anion: OH-

Question 5

What is the ionic equation, colour and anion for copper sulphate + sodium hydroxide?

Answer 5

Ionic equation: Cu2+ (aq) + 2OH- => Cu(OH)2 (s)
Colour: blue ppt
Anion: OH-

Question 6

What is the formula, colour, equation and ligand for copper sulphate + hydrochloric acid?

Answer 6

Formula: [CuCl4]2-
Colour: blue to yellow (green solution due to mixing)
Equation: [Cu(H2O)6]2+ + 2OH- <=> [CuCl4]2- + 6H2O
Ligand: Cl-

Question 7

What are the equations (two) colour and anion for copper sulphate + dilute ammonia?

Answer 7

Equations:
NH3 + H2O <=> NH4+ + OH-
Cu2+(aq) + 2OH- (aq) => Cu(OH)2 (s)

Question 8

What is the formula, equation, colour and ligand for copper sulphate + concentrated ammonia?

Answer 8

Formula: [Cu(NH3)4(H2O)2]2+
Equation: [Cu(H2O)4]2+ + 4NH3 <=> [Cu(NH3)4(H2O)2]2+ + 4H2O
Colour: blue to deep blue/violet solution
Ligand: NH3

Question 9

What is the colour, equation and anion for Iron (II) sulphate + OH-?

Answer 9

Colour: green ppt (foxy brown surface)
Equation: Fe2+ (aq) + 2OH- (aq) => Fe(OH)2 (s)
Anion: OH-

Question 10

What is a complex ion?

Answer 10

A central metal ion surrounded by groups called ligands.

Question 11

What is a ligand?

Answer 11

An anion or neutral molecule, with a lone pair of electrons which it donates to the central metal ion forming a dative covalent bond (coordinate bond)

Question 12

What is the coordination number?

Answer 12

The number of dative bonds to the central metal ion

Question 13

What is the shape name for a complex ion with a coordination number of 6?

Answer 13

Coord no: 6
Name: octahedral

Question 14

What is the shape name for a complex ion with the coord no 4?

Answer 14

Coord no: 4
Shape: tetrahedral

Question 15

What is the shape name for a complex ion with the coordination number 2?

Answer 15

Coord no: 2
Name: linear

Question 16

What is a Bidentate ligand? And does the coordination number change?

Answer 16

Some molecules have 2 atoms with lone pairs which can both form a dative bond to the central metal ion.
The coordination number doesn’t change due to there still being the same number of dative bonds formed to the central metal ion.

Question 17

What is a hexadentate ligand?

Answer 17

A ligand which consists of one central metal ion and one ligand which forms all 6 dative bonds to the central ion