Blue/purple = additions by Gorick

Introduction


Since the beginning of chemistry, coordination compounds have been known (mostly through accidental discoveries). An example of such compounds includes Prussian blue, an accidental discovery by Diesbach in 1704, an artists' pigments manufacturer. Frederick Augustus Genth, an assistant to Bunsen as the University of Marburg initiated the first serious study of cobalt-ammine complexes (the result of an inadvertent discovery). Instead of adding potassium hydroxide after precipitating the metals in his analytical group, Genth added ammonia to the mixture. He left the experiment, and upon his return, discovered that the mixture had crystallized and had formed into very beautiful crystals with pretty colours. However, Genth emigrated to America before he could do much more. In the following year, an American scientist, Oliver Wolcott Gibbs started an investigation and teamed up with Genth in 1856 to publish a paper in which the described thirty five cobalt-ammine complexes.

The term coordinate compounds (otherwise known as complex compounds) are used to describe molecules formed by the combination of ligands and metal ions. Ligands are atoms, ions, or molecules that donate an electron pair to the central metal, the central metal including all metal compounds, except for metal vapours, plasmas, and alloys. The ligands are bound to the metal through a coordinate covalent bond, which is formed when a lone electron pair is donated to an empty metal orbital. Coordinate compounds differ from ionic and covalent chemical bonds in that both the electrons in a bond come from the same atom. However, a coordinate bond is indistinguishable from covalent bonds after chemical bonding occurs.

The idea of coordinate compounds can be linked to the Lewis theory. The Lewis theory was extended from the Lowry-Bronsted Theory (the theory that an acid is a proton donor and a base is a proton acceptor). A Lewis acid is a compound or atom that can accept a lone electron pair. A Lewis base is a compound that can donate an electron pair. The purpose of this experiment is to synthesize and crystallize a coordinate compound and study its crystal structure.

Crystallization: The process of forming crystals from a liquid or gas. Angela Li


Materials
10.0 grams of copper sulfate pentahydrate (CuSO4•5H2O)
15 M Ammonia (NH3)
1X Balance
1X 250mL beaker
1X Safety googles
1X Evaporating dish
1X Beaker

Safety Considerations

Ammonia (NH
3(aq)):

Ammonia is a colorless gas. It has a very strong and sharp odour. According to the EU classification, ammonia is a hazardous, caustic, and corrosive. Thus, when the ammonia solution is used with a beaker in a reaction, it must be accompanied with a fume hood. Gloves and safety goggles must be worn when performing an experiment with ammonia.

Copper (II) Sulphate Pentahydrate (CuSO4 · 5H2O):
Copper (II) Sulphate Pentahydrate is blue in colour. It has no odour and is non-flammable. According to the EU classification, Copper (II) Sulphate is harmful and dangerous to the environment. It is considered a very acidic chemical and is to be handled with caution.

Heating:
When using the Bunsen burner, safety goggles must be worn. Gloves and aprons are highly recommended. Beaker, test tube, and flask tongs are used when appropriate. When using the hot plate, place all containers on top of the wired gauze to avoid spilling the substance on the hot plate.

Ethanol:
Ethanol is a highly flammable substance. Therefore, when handling ethanol, safety goggles are needed. Also, it is recommended to not place it near a flame source.

General Safety

Wear safety goggles when performing the lab experiment.
Know the location of the fire extinguisher, eye washer, and the chemical shower.
Tie back long hair.

Procedure
1.


Observations

Calculations

Conclusions

Discussion

Sources of Experimental Error