Caryn MartinBrittany Warren

Hannah Richardson                 3/17/2011

   Aluminum, Silver and Potassium

Abstract 

    The purpose of this lab is to separate the ions, aluminum, silver and potassium. This is achieved by adding different elements or compounds into the mixture. The first step was to divide up the ion mixture equally into four different test tubes. In the first test tube add sodium bromide and then centrifuge it. Then pour the liquid off into another test tube and repeat the adding of sodium bromide and centrifuging until the silver is all precipitated out. Then add sodium hydroxide to precipitate out the aluminum. Repeat the adding of the sodium hydroxide and centrifuging, like in the previous step, until the aluminum is all precipitated out. Then perform a flame test to test for the presence of potassium, a lilac colored flame is a positive result. The lab was a success, it worked perfectly the first time, with only a few minor changes that had to be made. With the changes that were made, there should be no problems executing it in the future.

    

    The purpose of this lab is to understand the separation of ions by adding compounds to precipitate out the elements, aluminum, silver, and potassium.   If these compounds are added then the ions should precipitate out.

   Introduction

Procedure 1. Lay all materials out2. Put on an apron and goggles. Also, make sure that closed toe shoes are worn. 3. Divide the ion mixture equally into four test tubes. Therefore, if a mistake is made then there is more mixture to fall back on. 4. Label the test tubes that have the ion mixture in them.5. Put the test tubes with the remaining three-fourthsof the ion mixture on a test tube rack.6. Take the dropper and add 10 drops of the first compound sodium bromide, which will be in liquid form, to one of the test tubes that is one-fourth full of the ion mixtre. By adding the first compound sodium bromine to the mixture, it will precipitate out the silver. 7. Put the test tube in the centrifuge, with a test tube that has the same amount of water, on the opposite side to balance it out, (make sure you have labed which one is the ion mixture and which is water). Turn on centrifuge on and let it run for a couple of minutes. Turn it off, then observe the results. 

Procedure cont.

8. All the solid silver should be at the bottom of the test tube after it is taken out of the centrifuge. Pour the liquid mixture into another testube. Leaving behind silver, stuck to the side of the test tube.9. Drop 5 more drops of sodium bromine into the mixture that was poured off from the silver. If silver is still precipitating out then add 10 more drops of sodium bromine into the mixture. This should precipitate out any remaining silver. Keep repeating steps 5-8 until all of the silver is precipitated out. 10. Next add 15 drops of liquid NaOH (sodium hydroxide) to the ion mixture. 11. By droping the NaOH into the mixture this will precipate out aluminum into a solid. Place in centrifuge and repeat steps 7 and 8. 

Procedure

12. For the last element dip a wooden splint into the remaining mixture and let it soak for a couple of minutes. 13. Once, it is done soaking hold the end of it over the Bunsen burner flame, a violet or lilac color flame should appear. This is a postive result for the presence of potassium. Initally a bright orange flame will appear, this is caused by the sodium burning. 14. Every element has sucessfully been precipitated out.

Observations

Upon receiving the ion mixture, the  mixture was a clear, liquid.    

Observations cont.

After sodium bromide (NaBr) was added the mixture turned foamy and white.

Observations cont.

After the mixture was centrifuged, a whitish, grey substance was stuck to the side of the test tube.

Observations cont.

After centrifuge, and transfer of ion mixture into a new test tube, leaving silver behind, 5 more drops of NaBr were added. Again a foamy, white substance was in the test tube.  

Observations cont.

After centrifuging this sample, a whitish, grey substance remained.

Observations cont.

After another 5 drops of sodium bromide was added for a third time, the sample was cloudy.

Observations cont.

After the sample was centrifuged, a small amount of silver remained on the side of the test tube. After 5 more drops of NaBr were added no cloudiness was observed.