2.6 Reactions of aqueous ions

Question 1

What is formed when Fe²⁺ reacts with water?

Answer 1

Forms [Fe(H₂O)₆]²⁺

Hexa-aqua iron

Question 2

What is formed when Cu²⁺ reacts with water?

Answer 2

Forms [Cu(H₂O)₆]²⁺

Hexa-aqua copper

Question 3

What is formed when Fe³⁺ reacts with water?

Answer 3

Forms [Fe(H₂O)₆]³⁺

Hexa-aqua iron

Question 4

What is formed when Al³⁺ reacts with water?

Answer 4

Forms [Al(H₂O)₆]³⁺

Hexa-aqua aluminium

Question 5

Which is more acidic [M(H₂O)₆]³⁺ or [M(H₂O)₆]²⁺?

Answer 5

[M(H₂O)₆]³⁺

Question 6

Explain why [M(H₂O)₆]³⁺ is more acidic?

Answer 6

• Has a higher charge and a smaller size.
• Therefore, the 3+ charge is more polarising.
• This attracts the e¯ from the oxygen lone pair on water ligands.
• This weakens the O-H bond on the water ligands.
• Makes it easier for the release of H⁺ from these bonds.
• H⁺ dissociates more, and therefore is more acidic.

Question 7

How does [Fe(H₂O)₆]²⁺ react with a little bit of NaOH/NH₃?

Answer 7

• Partial hydrolysis of water ligands.

- Results in neutralisation.

Question 8

[Fe(H₂O)₆]²⁺ + OH¯/NH₃ →

Answer 8

[Fe(OH)₂(H₂O)₄] + 2H₂O

Question 9

What is the observation for [Fe(H₂O)₆]²⁺ + OH¯/NH₃?

Answer 9

Green precipitate (solution)

Question 10

How does [Cu(H₂O)₆]²⁺ react with a little bit of NaOH/NH₃?

Answer 10

• Partial hydrolysis of water ligands.

- Results in neutralisation.

Question 11

[Cu(H₂O)₆]²⁺ + OH¯/NH₃ →

Answer 11

[Cu(OH)₂(H₂O)₄] + 2H₂O

Question 12

What is the observation for [Cu(H₂O)₆]²⁺ + OH¯/NH₃?

Answer 12

Blue precipitate (solution)

Question 13

How does [Fe(H₂O)₆]²⁺react in excess OH¯/NH₃?

Answer 13

Same as in a little bit, just neutralisation.

Question 14

How does [Cu(H₂O)₆]²⁺ react in excess OH¯?

Answer 14

Same as in a little bit, just neutralisation.

Question 15

How does [Fe(H₂O)₆]³⁺ react with a little bit of NaOH/NH₃?

Answer 15

• Partial hydrolysis of water ligands.

- Results in neutralisation.

Question 16

How does [Al(H₂O)₆]³⁺ react with a little bit of NaOH/NH₃?

Answer 16

• Partial hydrolysis of water ligands.

- Results in neutralisation.

Question 17

[Fe(H₂O)₆]³⁺ + OH¯ / NH₃→

Answer 17

[Fe(OH)₃(H₂O)₃] + 3H₂O

Question 18

[Al(H₂O)₆]³⁺ + OH¯/NH₃ →

Answer 18

[Al(OH)₃(H₂O)₃] + 3H₂O

Question 19

What is the observation for [Fe(H₂O)₆]³⁺ + OH¯/NH₃?

Answer 19

Brown precipitate (solution)

Question 20

What is the observation for [Al(H₂O)₆]³⁺ + OH¯/NH₃?

Answer 20

White precipitate (solution)

Question 21

How does react [Fe(H₂O)₆]³⁺ in excess OH¯/NH₃?

Answer 21

Same as in a little bit, just neutralisation.

Question 22

How does react [Al(H₂O)₆]³⁺ in excess OH¯?

Answer 22

Forms [Al(OH)₄]¯

Question 23

How does [Fe(H₂O)₆]²⁺ react in excess NH₃?

Answer 23

Same as in a little bit, just neutralisation.

Question 24

How does [Cu(H₂O)₆]²⁺ react in excess NH₃?

Answer 24

• Neutralisation to form [Cu(OH)₂(H₂O)₄]

- Then does ligand substitution to form [Cu(NH₃)₄(H₂O)₂]²⁺

Question 25

What is the observation for [Cu(H₂O)₆]²⁺ + excess NH₃?

Answer 25

Dark Blue solution

Question 26

How does react [Al(H₂O)₆]³⁺ in excess NH₃?

Answer 26

Same as in a little bit, just neutralisation.

Question 27

What is the observation for [Al(H₂O)₆]³⁺ + excess OH¯?

Answer 27

Colourless solution (see-through)

Question 28

How does [Al(H₂O)₆]³⁺ react with CO₃¯?

Answer 28

• Neutralisation

Forms [Al(OH)₃(H₂O)₃]

Question 29

What the observation for [Al(H₂O)₆]³⁺ + CO₃¯?

Answer 29

White precipitate + CO₂

Question 30

How does [Fe(H₂O)₆]³⁺ react with CO₃¯?

Answer 30

• Neutralisation

Forms [Fe(OH)₃(H₂O)₃]

Question 31

What the observation for [Fe(H₂O)₆]³⁺ + CO₃¯?

Answer 31

Brown precipitate + CO₂

Question 32

How does [Fe(H₂O)₆]²⁺ react with CO₃¯?

Answer 32

Forms SALT + WATER

Question 33

[Fe(H₂O)₆]²⁺ + CO₃¯ =

Answer 33

FeCO₃ + 6H₂O

Question 34

What the observation for [Fe(H₂O)₆]²⁺ + CO₃¯?

Answer 34

Green precipitate

Question 35

How does [Cu(H₂O)₆]²⁺ react with CO₃¯?

Answer 35

Forms SALT + WATER

Question 36

[Cu(H₂O)₆]²⁺ + CO₃¯ =

Answer 36

CuCO₃ + 6H₂O

Question 37

What the observation for [Cu(H₂O)₆]²⁺ + CO₃¯?

Answer 37

Blue precipitate