Perform the following steps in a fume hood.
1. Heat about 300mL of water in a 600mL beaker and maintain at a moderate boil.
2. In an evaporating dish, combine 4.0g of Cobalt (II) Chloride Hexahydrate with 10mL of distilled water. To this, add 15mL of 10% ethylenediamine (en).
Place the evaporating dish on top of the beaker of boiling water. Stir the mixture over this steam bath for 40 minutes; maintain the volume of the solution at about 20mL by occasionally adding small portions of water. During this process, the Co2+ is oxidized to Co3+ by the Oxygen in the Air. Good agitation is necessary to promote solvation of the oxygen.
3. Add 12mL of Concentrated 12M HCl. Continue heating and stirring, without addition of water, until a thin slurry of crystals has formed. (Note: Stopping the evaporation at the right time is critical to the success of the synthesis. Stopping too soon will give a poor yield of the product; stopping too late will give an impure product.)
Cool the slurry to Room Temperature by setting the evaporating dish on the lab bench. Stir occasionally for 15 minutes.
4. Filter the mixture using a Buchner funnel with Side-Arm Flask attached to an aspirator.
When the draining from the Buchner funnel has essentially stopped, add 5mL of 6M HCl to the funnel and gently stir up the mixture with a spatula, taking care not to tear the filter paper. (Do not use Pure Water to wash your product. If you do, the complex will decompose.)
If the product is still brown or blue, repeat the washing process with 6M HCl. If the product is pure green, skip the washing to avoid loss of product.
5. Transfer the moist crystals of the product to a clean watch glass. Dry the material on the steam bath. During the last stages of drying, powder the material on the watch glass by scrapping and pressing with a spatula.
6. Transfer the dried product to a previously weighed 3-dram vial. Label this vial with your Name(s), Product Name, Product Formula, Mass Product Obtained and the Date.