Transition Metals and Coordination Compounds- Chloro Complexes of Cobalt (II)

Chloro Complexes of Cobalt (II)

Description: The pink hexaaqua complex of cobalt is converted to the blue complex by addition of concentrated hydrochloric acid. The blue chloro complex is converted back to the pink hexaaqua complex by adding more water.

Source: Shakhashiri, B.Z.  Chemical Demonstrations: A Handbook for Teachers of Chemistry

Year: 1983   Vol: 1   Page: 280

Keywords: Complex ions, Cobalt (II), Equilibrium, Chloride Ion

Rating:

Hazard: Medium

• Skin corrosion hazard
• Acute toxicity – oral
• Inhalation hazard
• Aquatic toxicity
• Serious eye damage
• Reproductive toxicity
• Carcinogenicity
• Germ cell mutagenicity
• Corrosive to metals
• Skin and respiratory sensitization
• Specific organ toxicity- single exposure – lungs

Effectiveness: Good

• Results are clearly observable without guidance
• Good connection from demo to course material
• High reliability
• Time to results are low
• Obvious contrast between systems behavior
• Mild effects are seen by audience

Difficulty: Medium

• Some sequential manipulations
• Use of toxic chemicals
• Volume-dependent addition for proper results
• Prior training recommended
• Reaction involving risk of inhalation
• Simple procedures
• Simple manipulations for most to perform

Safety Precautions:

• Eye protection required
• Gloves required
• Perform in a well-ventilated area
• Downdraft hood recommended
• Avoid exposure to fumes or liquids
• Absorbent material on hand
• Sodium bicarbonate on hand
• Perform on a chemically resistant surface
• Prevent release of reagents to the environment

Class: Transition Metals

Division: General, Inorganic Chemistry

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