Place approximately 2 mL. of 0.1 M Co(H_2O)_6^=2 solution in a 6\" test tube. Re
ID: 1062326 • Letter: P
Question
Place approximately 2 mL. of 0.1 M Co(H_2O)_6^=2 solution in a 6" test tube. Record the color of the Co(H_2O)_6^+2 solution in your Data Sheet. (Note: You might want to use a graduated cylinder to measure 2 mL. Also, Co(H_2O)_6^+2 is also known asCoC1_2-6H_2O, or sometimes plainly as CoC1_2. Using a dropper, carefully add concentrated HCl dropwise into the Co(H_2O)_6^+2 solution until the reaction changes color (Note: At least 20 drops but no mote than 35 drops). Gently mix the contents of test tube by holding the upper portion of the test tube and rotating the test tube in a circular motion. CAUTION: Never put any part of your body in contact with the concentrated acid. Do NOT put your finger over the test tube to shake it. Watch the instructor demonstrate the proper addition of the acid and the mixing of the contents of the test tube. Record the color of this product in your Data Sheet. Prepare an ice bath by placing about half a handful of ice into a 250 mL beaker. Then add approximately 50 mL distilled into the beaker. Place the test tube in the previous step into the ice bath until the color changes. Record the color ol Hits solution into the Data Sheet. Remove the test tube from the ice bath, and warm the tube using the palm of your hand until the color change. Record the color of this solution into the Data Sheet. Using a wash bottle, slowly add distilled water into the test tube above until the color change. Record the color of this solution into the Data Sheet. (If time permits, gently heat the test tube using a Bunsen burner. Instructor will demonstrate the proper technique. Do not point the test tube at anyone. Heat only the upper part of the liquid by passing it over the blue flame back and forth. Discard all waste into the proper waste container.Explanation / Answer
1. The colour of the complex cobalt hexahydrate dication is light purple to pink in the test tubes.
2. 20 to 25 drops of concentrated HCl was added to the test tubes. After some time no change in colour was noticed.
3. After the solutions were ice cooled the light pink colour was changed to blue.
4. The colour remains blue after the solutions were warmed to room temperature. It is because excess chloride ions reacted with the complex before and turned it to tetrachloro cobalt (II) di anion which is blue in colour.