COMPLEX IONS LAB
Objectives
 To observe transition metals forming complex ions with the ammine, chloride, and thiocyanato ion
ligands.
 To practice writing reaction equations, naming complex ions, and determining coordination numbers.
Define the following:

Coordinate covalent bond:

Ligand:

Coordination number:
*
Net ionic equation:
Evidence that a chemical reaction has occurred include the following:
1. color change
2. formation of a precipitate
AMMINE COMPLEXES (Aqueous ammonia is used as a source of the ammine, NH3 ligand.)
1. Copper (II) ion color: ______________________
a. To approximately 1 mL of a solution containing the copper (II) ion, add a few drops of 1.0 mol dm-3
ammonia solution until an insoluble precipitate of copper (II) hydroxide forms.
b. Record your observations:
Write the balanced, net ionic equation showing the above reaction:
c. Add excess ammonia solution until the precipitate dissolves and the soluble ammine complex ion
forms.
d. Record the color of the complex ion: _______________________
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
e. Name the complex ion: _________________________________________________________
f. State the oxidation number of the transition metal in the complex ion: _____
g. State the coordination number of the complex ion: _____
h. Draw the Lewis structure for the complex ion and state the shape of the complex.
2. Zinc ion color: _________________
a. To approximately 1 mL of a solution containing the zinc ion, add a few drops of 1.0 mol dm-3
ammonia solution until an insoluble precipitate of zinc hydroxide forms.
b. Record your observations:
Write the balanced, net ionic equation showing the above reaction:
c. Add excess ammonia solution until the precipitate dissolves and the soluble ammine complex ion
forms.
d. Record the color of the complex ion: ___________________
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
e. Name the complex ion: _________________________________________________________
f. State the oxidation number of the transition metal in the complex ion: _____
g. State the coordination number of the complex ion: _____
h. Draw the Lewis structure for the complex ion and state the shape of the complex.
CHLORO COMPLEXES (Concentrated hydrochloric acid is used as a source of the chloro, Cl- ligand)
In these reactions no precipitate forms. The complex ion forms immediately on the addition of the ligand.
* Because chloride ions are fairly large, you can only fit 4 of them around the central ion - that's why most
chloro complexes usually have a coordination number of 4, regardless of the charge on the metal ion.
3. Copper (II) ion color: ________________
a. To approximately 1 mL of a solution containing the copper (II) ion, add a few drops of concentrated
(6M) hydrochloric acid.
b. Record the color of the complex ion: ____________________
Write the balanced, net ionic equation for the formation of the complex ion:
c. Name the complex ion: _________________________________________________________
d. State the oxidation number of the transition metal in the complex ion: _____
e. State the coordination number of the complex ion: _____
f. Draw the Lewis diagram for the complex ion and state the shape of the complex.
4. Iron (III) ion color: __________________
a. To approximately 1 mL of a solution containing the iron (III) ion, add a few drops of concentrated
(6M) hydrochloric acid.
b. Record the color of the complex ion: ____________________
Write the balanced, net ionic equation for the formation of the complex ion:
c. Name the complex ion: _________________________________________________________
d. State the oxidation number of the transition metal in the complex ion: _____
e. State the coordination number of the complex ion: _____
f. Draw the Lewis diagram for the complex ion and state the shape of the complex.
5. Cobalt (II) ion color: ___________________
a. To approximately 1 mL of a solution containing the cobalt (II) ion, add a few drops of concentrated
(6M) hydrochloric acid.
b. Record the color of the complex ion: ____________________
Write the balanced, net ionic equation for the formation of the complex ion:
c. Name the complex ion: _________________________________________________________
d. State the oxidation number of the transition metal in the complex ion: _____
e. State the coordination number of the complex ion: _____
f. Draw the Lewis diagram for the complex ion and state the shape of the complex.
THIOCYANATO COMPLEXES (Potassium thiocyanate is a source of the thiocyanate, SCN- ligand.)
If dilute [SCN]− is added to a solution containing iron (III) ions, a complex ion with the formula
[Fe(NCS)(H2O)5]2+ is formed.
6. Iron (III) ion color: ______________________
a. To approximately 1 mL of a solution containing the iron (III) ion, add a little 0.1 mol dm-3 potassium
thiocyanate.
b. Record the color of the complex ion: ____________________
c. Name the complex ion: _________________________________________________________
d. State the oxidation number of the transition metal in the complex ion: _____
e. State the coordination number of the complex ion: _____
f. Draw the Lewis diagram for the complex ion and state the shape of the complex.
Extension Questions
7. Formation of an Ammine Complex
a. Ammonia is added to a solution containing the silver ion which produces complex ion.
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
(Remember that, in general, the number of ligands is usually twice the charge on the metal ion.)
b. Name the complex ion: _________________________________________________________
c. State the oxidation number of the transition metal in the complex ion: _____
d. State the coordination number of the complex ion: _____
8. Formation of an Ammine Complex
a. Ammonia is added to a solution containing the iron (III) ion which produces a complex ion.
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
(Remember that, in general, the number of ligands is usually twice the charge on the metal ion.)
b. Name the complex ion: _________________________________________________________
c. State the oxidation number of the transition metal in the complex ion: _____
d. State the coordination number of the complex ion: _____
9. Formation of an Ammine Complex
a. Ammonia is added to a solution contain the cobalt (III) ion which produces a complex ion.
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
(Remember that, in general, the number of ligands is usually twice the charge on the metal ion.)
b. Name the complex ion: _________________________________________________________
c. State the oxidation number of the transition metal in the complex ion: _____
d. State the coordination number of the complex ion: _____
10. Formation of a Chloro Complex
a. Concentrated (6M) hydrochloric acid is added to a solution contain the nickel ion which produces a
yellow-brown complex ion.
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
(Because chloride ions are fairly large, you can only fit 4 of them around the central metal ion - that's why
most chloro complexes usually have a coordination number of 4, regardless of the charge on the metal ion.)
b. Name the complex ion: _________________________________________________________
c. State the oxidation number of the transition metal in the complex ion: _____
d. State the coordination number of the complex ion: _____
11. Formation of a Chloro Complex
a. Concentrated (6M) hydrochloric acid is added to a solution contain the zinc ion which produces a
complex ion.
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
(Because chloride ions are fairly large, you can only fit 4 of them around the central metal ion - that's why
most chloro complexes usually have a coordination number of 4, regardless of the charge on the metal ion.)
b. Name the complex ion: _________________________________________________________
c. State the oxidation number of the transition metal in the complex ion: _____
d. State the coordination number of the complex ion: _____
11. Formation of a Chloro Complex
a. Concentrated (6M) hydrochloric acid is added to a solution contain the iron (II) ion which produces a
complex ion.
Write the balanced, net ionic equation for the formation of the complex ion. Include states.
(Because chloride ions are fairly large, you can only fit 4 of them around the central metal ion - that's why
most chloro complexes usually have a coordination number of 4, regardless of the charge on the metal ion.)
b. Name the complex ion: _________________________________________________________
c. State the oxidation number of the transition metal in the complex ion: _____
d. State the coordination number of the complex ion: _____