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: Shakahashiri, 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: High
- Inhalation hazard
- Acute toxicity hazard – oral
- Skin corrosion hazard
- Corrosive to metals
- Reproductive toxicity hazard
- Carcinogenicity hazard
- Germ cell mutagenicity hazard
- Skin and respiratory sensitization
- Short term aquatic toxicity hazard
- Long term aquatic toxicity hazard
- Specific organ toxicity – single exposure – lungs
- Serious eye damage
Effectiveness: Good
- Results are clearly observable without guidance
- Good connection from demo to course material
- High reliability
- Time to results is low
- System contrast is obvious
- Mild effects are seen by audience
Difficulty: Medium
- Use of toxic compounds
- Reaction involving risk of inhalation
- Simple procedures
- Simple manipulations for most to perform
- Sequential manipulations
- Use of toxic chemicals
- Volume-dependent addition for proper results
Safety Precautions:
- Perform in a well-ventilated area
- Downdraft hood recommended
- Eye protection required
- Gloves are required
- Absorbent material on hand
- Sodium bicarbonate on hand
- Use of chemically resistant surface
- Avoid exposure to mists and vapors
- Prevent release of reagents to the environment
Class: Equilibrium, Transition Metals Chemistry, Coordination Compounds
Division: General, Inorganic Chemistry
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