I2: 24 Reactions of Inorganic Compounds

Question 1

In aqueous solution, what are the formulas for 2+ and 3+ metal-aqua ions formed?

Answer 1

[M(H2O)6]2+
[M(H2O)6]3+

Question 2

Between [M(H2O)6]2+ and [M(H2O)6]3+, which one is more acidic?

Answer 2

[M(H2O)6]3+

Question 3

How do metal hydroxides show amphoteric character?

Answer 3

They dissolve in both acids and bases.

Question 4

Why is the acidity of [M(H2O)6]3+ greater than that of [M(H2O)6]2+?

Answer 4

Metal 3+ ions are small and have a larger charge, so they have a higher charge density.
3+ ions are more polarising so attract electrons from the oxygen atoms of the co-ordinated water molecules, weakening the O-H bond.
It’s more likely for a hydrogen ion to be released.

Question 5

What is the reaction of [Fe(H2O)6]2+ with OH-?

Dropwise and excess.

Answer 5

[Fe(H2O)6]2+(aq) + 2OH-(aq) -> Fe(H2O)4(OH)2(s) + 2H2O(l)

Dropwise - green precipitate forms
Excess - no visible change

Question 6

What is the reaction of [Fe(H2O)6]2+ with NH3?

Dropwise and excess.

Answer 6

[Fe(H2O)6]2+(aq) + 2NH3(aq) -> Fe(H2O)4(OH)2(s) + 2NH4+(aq)

Dropwise - green precipitate forms
Excess - no visible change

Question 7

What is the reaction of [Fe(H2O)6]2+ with CO32-?

Answer 7

Fe2+(aq) + CO32-(aq) -> FeCO3(s)

Green precipitate forms.

Question 8

What is the reaction of [Cu(H2O)6]2+ with OH-?

Dropwise and excess

Answer 8

[Cu(H2O)6]2+(aq) + 2OH-(aq) -> Cu(H2O)4(OH)2(s) + 2H2O(l)

Dropwise - blue precipitate forms
Excess - no visible change

Question 9

What is the reaction of [Cu(H2O)6]2+ with NH3?

Dropwise and excess?

Answer 9

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

Dropwise - blue precipitate forms
Excess - blue precipitate dissolves, forming a deep blue solution.

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

Question 10

What is the reaction of [Cu(H2O)6]2+ with CO32-?

Answer 10

Cu2+(aq) + CO32-(aq) -> CuCO3(s)

Blue-green precipitate forms.

Question 11

What is the reaction of [Al(H2O)6]3+ with OH-?

Dropwise and excess.

Answer 11

[Al(H2O)6]3+(aq) + 3OH-(aq) -> Al(H2O)3(OH)3(s) + 3H2O(l)

Dropwise - white precipitate forms
Excess - white precipitate dissolves, forming a colourless solution

Al(H2O)3(OH)3(s) + OH-(aq) -> [Al(H2O)2(OH)4]-(aq) + H2O(l)

Question 12

What is the reaction of [Al(H2O)6]3+ with NH3?

Dropwise and excess.

Answer 12

[Al(H2O)6]3+(aq) + 3NH3(aq) -> Al(H2O)3(OH)3(s) + 3NH4+(aq)

Dropwise - white precipitate forms
Excess - no visible change

Question 13

What is the reaction of [Al(H2O)6]3+ with CO32-?

Answer 13

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

White precipitate forms and effervescence occurs.

Question 14

What is the reaction of [Fe(H2O)6]3+ with OH-?

Dropwise and excess.

Answer 14

[Fe(H2O)6]3+(aq) + 3OH-(aq) -> Fe(H2O)3(OH)3(s) + 3H2O(l)

Dropwise - brown precpitate forms
Excess - no visible change

Question 15

What is the reaction of [Fe(H2O)6]3+ with NH3?

Dropwise and excess.

Answer 15

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

Dropwise - brown precpitate forms
Excess - no visible change

Question 16

What is the reaction of [Fe(H2O)6]3+ with CO32-?

Answer 16

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

Brown precipitate forms and effervesence occurs.