The solution was mixed and then spun again for 30 seconds 4 more drops of HCl

The solution was mixed and then spun again for 30

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observed. The solution was mixed and then spun again for 30 seconds. 4 more drops of HCl were added to yield more precipitate and the solution was spun again to separate the phases. 3 more drops still produced more white precipitate and so after more 30 second spinning 3 extra drops 6
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CHEM 7L Template, Expt 5 SP17 were added and no more white precipitate was observed. In total, 13 drops of 3M of HCl were added to precipitate all the Ag + ions present in the unknown. In the process the unknown solution changed color from blue to green. After the fifth spinning the supernatant was carefully decanted into a separate clean test tubes and parafilmed to prevent evaporation. The supernatant was set aside for approximately 15 minutes. Afterwards 10 drops of 6M NaOH were added and mixed. pH was checked to confirm that the solution was strongly basic. Orange precipitate formed. After the solution was centrifuged for 30 seconds, two phases were observed: clear colorless solution and orange precipitate. Supernatant and precipitate were mixed together and 7 drops of 6% H 2 O 2 were added to the solution with stirring. The unknown solution was placed in the water bath at 60°C and kept there for 4 minutes with constant stirring. After it was taken out of the water bath, the solution was spun for 30 seconds. The unknown was separated into a clear colorless solution and orange-brown precipitate. The supernatant was decanted and set aside. The precipitate was washed with approximately 1 mL of DI H 2 O. After the wash, 5 drops of 6M H 2 SO 4 were added to the precipitate and stirred. The solution was spun for 30 seconds. It changed color to blue-green. No precipitate was observed. The solution was split into two halves. To the other half of the solution 5 drops of 5M NH 4 OH were added. The solution changed from blue-green to very pale blue and some orange precipitate formed and dissolved. The pH showed that the solution is still acidic. 5 more drops were added and orange precipitate was observed. The pH test showed a slightly basic environment, so 5 extra drops were added and the third pH test showed strongly basic environment. The solution was centrifuged for 30 seconds and two phases were observed: clear-colorless solution with orange-brown precipitate. The unknown was mixed back together. 5 drops of dimethylglyoxime were added to the mixed solution. The unknown turned bright pink. Procedure and Observations for the Control : To the 20 drops of control solution 10 drops of 6M NaOH were added and mixed. pH was checked to confirm that the solution was strongly basic. Sludgy brown formed. After the solution was centrifuged for 30 seconds, two phases were observed: clear colorless solution and brown precipitate. Supernatant and precipitate were mixed together and 7 drops of 6% H 2 O 2 were added to the solution with stirring. The known solution was placed in the water bath at 60°C and kept there for 4 minutes with constant stirring. After it was taken out of the water bath, the solution was spun for 30 seconds. The known was separated into a clear white solution and black-brown precipitate. The supernatant was decanted and set
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  • Fall '11
  • BERNOILLES
  • Solubility, drops, Sludgy brown

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