Metal-aqua ions

Question 1

What is a co-ordinate bond?

Answer 1

One substance donating a pair of electrons to another

Question 2

When do metal-aqua complex ions form?

Answer 2

When metal ions dissolve in water, the water molecules form co-ordinate bonds with the metal ions

Question 3

In general, how many water molecules bond in a metal-aqua complex?

Answer 3

6

Question 4

Why are metal 3+ ions more acidic than metal 2+ ions?

Answer 4

• Metal 3+ ions have a higher charge density than metal 2+ ions
• Metal 3+ ions are much more polarising than the 2+ ions
• Metal 3+ ions attract electrons from the oxygen atoms from the co-ordinately bonded water molecules more strongly than the metal 2+ ions
• This means it is more likely an H+ ion will be released and then the solution will be more acidic

Question 5

What is the general overall equation when metal aqua ions act as bronsted Lowry acids?

Answer 5

[M(H₂O)₆]³⁺ + 3H₂O M(OH)₃(H₂O)₃ + 3H₃O+

Question 6

What is the first equation when a 3+ metal aqua ion complex reacts with water?

Answer 6

[M(H₂O)₆]³⁺ + H₂O [M(OH)(H₂O)₅]²⁺ + H₃O+

Question 7

What is the second equation when a 3+ metal aqua ion complex reacts with water?

Answer 7

[M(OH)(H₂O)₅]²⁺ + H₂O [M(OH)₂(H₂O)₄]⁺ + H₃O+

Question 8

What is the third equation when a 3+ metal aqua ion complex reacts with water?

Answer 8

[M(OH)₂(H₂O)₄]⁺+ H₂O M(OH)₃(H₂O)₃ + H₃O+

Question 9

What can some metal hydroxides be?

Answer 9

Amphoteric

Question 10

what does amphoteric mean?

Answer 10

They can act as both acids and bases

Question 11

What colour is [Cu(H₂O)₆]²⁺?

Answer 11

Blue solution

Question 12

What colour is [Fe(H₂O)₆]²⁺?

Answer 12

Green solution

Question 13

What colour is [Fe(H₂O)₆]³⁺?

Answer 13

Yellow solution

Question 14

What colour is [Al(H₂O)₆]³⁺?

Answer 14

Colourless solution

Question 15

What is formed when [Cu(H₂O)₆]²⁺ reacts with OH- or NH₃?

Answer 15

Cu(OH)₂(H₂O)₄ + 2H₂O

Question 16

What colour is Cu(OH)₂(H₂O)₄?

Answer 16

Blue precipitate

Question 17

What is formed when excess OH- is added to [Cu(H₂O)₆]²⁺?

Answer 17

No change
Cu(OH)₂(H₂O)₄
Blue precipitate

Question 18

What is formed when [Cu(H₂O)₆]²⁺ reacts with excess NH₃?

Answer 18

[Cu(NH₃)₄(H₂O)₂]²⁺ + 4H₂O

Question 19

What colour is [Cu(NH₃)₄(H₂O)₂]²⁺?

Answer 19

Deep blue solution

Question 20

What is formed when [Cu(H₂O)₆]²⁺ reacts with Na₂CO₃?

Answer 20

CuCO₃ + 6H₂O

Question 21

What colour is CuCO₃?

Answer 21

Green-blue precipitate

Question 22

What is formed when [Fe(H₂O)₆]²⁺ reacts with OH- or NH₃?

Answer 22

Fe(OH)₂(H₂O)₄ + 2H₂O

Question 23

What is formed when excess OH- is added to [Fe(H₂O)₆]²⁺ ?

Answer 23

No change
Fe(OH)₂(H₂O)₄
Green precipitate

Question 24

What is formed when [Fe(H₂O)₆]²⁺ reacts with excess NH₃?

Answer 24

No change
Fe(OH)₂(H₂O)₄
Green precipitate

Question 25

What is formed when [Fe(H₂O)₆]²⁺ reacts with Na₂CO₃?

Answer 25

FeCO₃ + 6H₂O

Question 26

What colour is Fe(OH)₂(H₂O)₄?

Answer 26

Green precipitate which goes brown standing in air

Question 27

What colour is FeCO₃?

Answer 27

Green precipitate

Question 28

What is formed when [Al(H₂O)₆]³⁺ reacts with OH- or NH₃?

Answer 28

Al(OH)₃(H₂O)₃ + 3H₂O

Question 29

What colour is Al(OH)₃(H₂O)₃ ?

Answer 29

White precipitate

Question 30

What is formed when [Al(H₂O)₆]³⁺ reacts with excess OH-?

Answer 30

[Al(OH)₄(H₂O)₂]-

Question 31

What is formed when [Al(H₂O)₆]³⁺ reacts with excess NH₃?

Answer 31

[Al(OH)₄(H₂O)₂]- | Colourless solution

Question 32

What is formed when [Al(H₂O)₆]³⁺ reacts with Na₂CO₃?

Answer 32

Al(OH)₃(H₂O)₃ + 3H₂O | Bubbles

Question 33

What colour is [Al(OH)₄(H₂O)₂]-?

Answer 33

Colourless solution

Question 34

What is formed when [Fe(H₂O)₆]³⁺ reacts with OH- or NH₃?

Answer 34

Fe(OH)₃(H₂O)₃ + 3H₂O

Question 35

What colour is Fe(OH)₃(H₂O)₃?

Answer 35

Brown precipitate

Question 36

What is formed when [Fe(H₂O)₆]³⁺ reacts with excess OH- or NH₃?

Answer 36

No further change Fe(OH)₃(H₂O)₃ Brown precipitate

Question 37

What is formed when [Fe(H₂O)₆]³⁺ reacts with Na₂CO₃?

Answer 37

Fe(OH)₃(H₂O)₃ | Bubbles