![]() Chemical Demonstrations: A Handbook for Teachers ofĬhemistry Wisconsin 1983 Vol. Ealy Chemical Demonstrations: A Sourcebook for Teachers. Use caution working with acidic solutions. Add water, however, and the equilibrium will shift back towards the pink hydrated species. If the chloride or cobalt concentrations increase, the equilibrium will also shift towards the blue anhydrous cobalt chloride. Cooling will shift the products towards the hydrated complex, which is more pink. If heat is added, the equilibrium will shift towards the cobalt chloride complex, which is blue in color. ![]() 2+(aq) + 4 Cl- 2-(aq) + 6H 2OĪ change in temperature or concentration of the ions will shift the equilibrium. Observe the colors of the solutions after several minutes.Īlternatively you can use the heat gun to increase the temperature of the cobalt chloride solutions to shift the equilibrium.Īn equilibrium exists between a hydrated cobalt species and anhydrous cobalt chloride, both have an oxidation state of 2+. Place one of each tube in the ice bath.Ĥ. Place one of each tube in the hot water.ģ. Cobaltous chloride is added to silica gel and activated alumina type desiccant as a moisture. The blue anhydrous form can be regenerated by heating at 52-56 C. On exposure to moist air, anhydrous cobaltous chloride absorbs water forming pink-color hexahydrate crystals. Hot plate is located in the top drawer opposite the chemical storage cabinets or on the center bench. Cobaltous chloride is most commonly used as a color indicator of moisture. ‡Test tubes with pre-prepared solutions and beakers are located in the solutions cabinet. ice water bath (get ice from Gen chem labs prior to class). ![]() 2 Pre-prepared test tubes with aqueous cobalt chloride (purple solutions)‡ in beaker.2 Pre-prepared test tubes with cobalt chloride and HCl (pink solutions)‡ in beaker.The tube placed in cold water will turn more pink. The tube placed in hot water will turn blue. ![]() Any impurities present will usually tend to raise the boiling. Using a thermometer, you can check if the boiling point is exactly 100 oC. A sample of the liquid is placed in a suitable container such as a boiling tube and gently heated.
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