Aqueous ions in solution

Question 1

The addition of aqueous sodium carbonate to a solution containing
[Fe(H2O)6]
3+(aq) ions.

Answer 1

Brown ppt/solid

Gas evolved/effervescence

2[Fe(H2O)6]3+ + 3CO32– → 2Fe(H2O)3(OH)3+ 3CO2 + 3H2O

Question 2

The addition of aqueous sodium hydroxide, dropwise until in excess, to a solution
containing [Al(H2O)6]
3+(aq) ions

Answer 2

White ppt/solid

Colourless Solution

-[Al(H2O)6]3+ + 3OH– → Al(H2O)3(OH)3 + 3H2O

Question 3

The addition of dilute aqueous ammonia, dropwise until in excess, to a solution
containing [Cu(H2O)6]
2+(aq) ions.

Answer 3

-Blue ppt/solid
-(dissolves to give a) deep blue solution

-[Cu(H2O)6
]
2+ + 2NH3
→ Cu(H2O)4
(OH)2
+ 2NH4
+
-Cu(H2O)4
(OH)2
+ 4NH3
→ [Cu(H2O)2
(NH3
)4
]
2+ + 2OH–
+ 2H2O

Question 4

The addition of concentrated hydrochloric acid, dropwise until in excess, to a
solution containing [Cu(H2O)6]
2+(aq) ions.

Answer 4

-Green/yellow solution
-[Cu(H2O)6
]
2+ + 4Cl–
→ [CuCl4
]
2– + 6H2O

Question 5

In what way can NH3 act as a LEWIS base

Answer 5

electron pair donor

Question 6

State what is observed when an excess of aqueous ammonia reacts with an
aqueous iron(II) salt. Write an equation for this reaction.

Answer 6

Pale green solution
Green precipitate formed

Insoluble in excess ammonia