Reactions of Ions in Aqueous Solution

Question 1

Define a lewis acid

Answer 1

Electron pair acceptor

Question 2

Define a lewis base

Answer 2

Electron pair donor

Question 3

Explain what the ligand in the formation of complex ions acts as and why

Answer 3

The ligand is the Lewis base because it is donating a pair of electrons in the dative covalent bond and the metal ion is the Lewis acid

Question 4

What metals form the metal aqua ions [M(H2O)6]2+ in aqueous solution

Answer 4

M = Fe (green) and Cu (blue)

Question 5

What metals form the metal aqua ions [M(H2O)6]3+ in aqueous solution

Answer 5

Al (colourless) and Fe (violet)

Question 6

What is the acidity or hydrolysis reactions which happen in aqueous solutions of metal ions

Answer 6

[M(H2O)6]2+ + H2O = [M(H2O)5(OH)]+ + H3O+

IT IS A REVERSIBLE REACTION

Question 7

State and explain the difference in acidity of [M(H2O)6]3+ and [M(H2O)6]2+

Answer 7

[M(H2O)6]3+ is more acidic.
The 3+ metal ions have a higher charge density and have greater polarising power.
The greater the polarising power, the more strongly it attracts the water molecule.
This weakens the O-H bond so it breaks more easily and releases H+ ions.

Question 8

Colour of [Fe(H2O)6]2+

Answer 8

Green solution

Question 9

Colour of [Cu(H2O)6]2+

Answer 9

Blue solution

Question 10

Colour of [Fe(H2O)6]3+

Answer 10

Purple solution

Question 11

Colour of [Al(H2O)6]3+

Answer 11

Colourless solution

Question 12

Colour of Fe(H2O)4(OH)2

Answer 12

Green precipitate which goes brown on standing in air

Question 13

Colour of Cu(H2O)4(OH)2

Answer 13

Blue precipitate

Question 14

Colour of Fe(H2O)3(OH)3

Answer 14

Brown precipitate

Question 15

Colour of Al(H2O)3(OH)3

Answer 15

White precipitate

Question 16

Equation for the reaction between [Fe(H2O)6]2+ and NaOH

Answer 16

[Fe(H2O)6] 2+ (aq) + OH– (aq) → [Fe(H2O)5(OH)] + (aq) + H2O (l)
[Fe(H2O)5(OH)] + (aq) + OH– (aq) → Fe(H2O)4(OH)2 (s) + H2O (l)

OR full equation :

[Fe(H2O)6] 2+(aq) + 2OH– (aq) → Fe(H2O)4(OH)2 (s) + 2H2O (l)

Question 17

Equation for the reaction between [Cu(H2O)6]2+ and NaOH

Answer 17

[Cu(H2O)6] 2+ (aq) + 2OH– (aq) → Cu(H2O)4(OH)2 (s) + 2H2O (l)

Question 18

Equation for the reaction between [Fe(H2O)6]3+ and NaOH

Answer 18

[Fe(H2O)6]3+ (aq) + 3OH– (aq) → Fe(H2O)3(OH)3 (s) + 3H2O (l)

Question 19

Equation for the reaction between [Al(H2O)6]3+ and NaOH

Answer 19

[Al(H2O)6]3+ (aq) + 3OH– (aq) → Al(H2O)3(OH)3 (s) + 3H2O (l)

Question 20

What happens when excess NaOH is added to the aqueous solutions of metal ions

Answer 20

No further change with :

Iron (II)
Copper (II)
Iron (III)

forms colourless solution of [Al(OH)4]- with Al (III)

Question 21

Equation for aluminium hydroxide dissolving in excess NaOH

Answer 21

Al(OH)3(H2O)3 (s) + NaOH (aq) → Na [Al(OH)4] (aq) + 3H2O (l)

Question 22

Equation for aluminium hydroxide reacting with and dissolving in dilute HCl

Answer 22

Al(OH)3(H2O)3 (s) + 3HCl (aq) → [Al(H2O)6] 3+ (aq) + 3Cl- (aq)

Question 23

Equation for reaction between aqueous solution of Cu(II) and NH3 (aq)

Answer 23

[Cu(H2O)6] 2+ (aq) + 2NH3 (aq) → Cu(H2O)4(OH)2 (s) + 2NH4+ (aq)

SAME PRODUCT FORMED AS WITH NAOH

Question 24

Equation for reaction between aqueous solution of Fe(III) and NH3 (aq)

Answer 24

[Fe(H2O)6] 3+ (aq) + 3NH3 (aq) → Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)

SAME PRODUCT FORMED AS WITH NAOH

Question 25

What reaction occurs when excess NH3 is added to Copper (II) in aqueous solution

Answer 25

Ligand substitution

Question 26

Reaction of copper (II) with excess NH3

Answer 26

Cu(H2O)4(OH)2 (s) + 4NH3 (aq) → [Cu(NH3)4(H2O)2 ]2+ (aq) + + 2OH- (aq) + 2H2O (l)

Question 27

Colour of [Cu(NH3)4(H2O)2 ]2+

Answer 27

Deep blue solution

Question 28

Reaction of Iron (II), Iron (III) and Al (III) with excess NH3

Answer 28

No further change

Question 29

Colour of FeCO3 (s)

Answer 29

Green precipitate

Question 30

Colour of CuCO3 (s)

Answer 30

Blue-green precipitate

Question 31

Equation for the reaction between aqueous iron (II) ions and Na2CO3

Answer 31

[Fe(H2O)6] 2+ (aq) + CO32- (aq) → FeCO3 (s) + 6H2O (l)

Question 32

Equation for the reaction between aqueous copper (II) ions and Na2CO3

Answer 32

[Cu(H2O)6] 2+ (aq) + CO32- (aq) → CuCO3 (s) + 6H2O (l)

Question 33

Equation for the reaction between aqueous aluminium (III) ions and Na2CO3

Answer 33

2[Al(H2O)6]3+ + 3CO32− (aq) → 2Al(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)

Question 34

Equation for the reaction between aqueous iron (III) ions and Na2CO3

Answer 34

2[Fe(H2O)6]3+ (aq) + 3CO32− (aq) → 2Fe(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)

Question 35

What is formed when M (II) ions react with conc HCL

Answer 35

[MCl4]2-

Question 36

Colour of [FeCl4]2-

Answer 36

Yellow solution

Question 37

Colour of [CuCl4]2-

Answer 37

green solution

Question 38

Colour of [FeCl4]-

Answer 38

Yellow solution

Question 39

Colour of [AlCl4]-

Answer 39

Colourless solution