24 - Reactions of inorganic compounds in aqueous solutions

Question 1

What metal-aqua irons are formed by Fe (II) and Cu?

Answer 1

[M(H2O)6]2+

Question 2

What metal-aqua irons are formed by Fe (III) and Al?

Answer 2

[M(H2O)6]3+

Question 3

Why is [M(H2O)6]+3 more acidic than [M(H2O)6]+2?

Answer 3

1. Greater charge density
2. Weakens polar bond in H2O ligand more
3. More H+ released

Question 4

Which metal hydroxides show amphoteric character?

Answer 4

Al(OH)3

Question 5

What colour precipitate does Fe2+ form?

Answer 5

Green

Question 6

What colour precipitate/solution does Fe3+ form?

Answer 6

Brown

Question 7

What colour precipitate does [Cu(H2O)6]2+?

Answer 7

Blue

Question 8

What colour solution does [Cu(H2O)6]2+ form with NaOH?

Answer 8

Blue

Question 9

Give the reactions of [Cu(H2O)6]2+ with NH3, excess NH3, Na2CO3.

Include products, and observations

Answer 9

NH3: Cu(H2O)4(OH)2, blue precipitate
Excess NH3: [Cu(H2O)2(NH3)4]2+ deep-blue solution
Na2CO3: CuCO3 blue-green ppt

Question 10

Give the reactions of [Fe(H2O)6]3+ with NaOH, excess NaOH, NH3, excess NH3, Na2CO3.

Include products, and observations.

Answer 10

Purple solution
NaOH: Fe(H2O)3(OH)3 brown ppt
Excess NaOH: No further change
NH3: Fe(H2O)3(OH)3 brown ppt
Excess NH3: No further change
Na2CO3: Fe(H2O)3(OH)3 brown ppt and CO2 gas evolved

Question 11

Give the reactions of [Al(H2O)6]3+ with NaOH, excess NaOH, NH3, excess NH3, Na2CO3.

Answer 11

Colourless solution
NaOH: Al(H2O)3(OH)3 white ppt
Excess NaOH: [Al(OH)4]- colourless solution
NH3: Al(H2O)3(OH)3 white ppt
Excess NH3: no further change
Na2CO3: Al(H2O)3(OH)3 white ppt and CO2 gas evolved