The procedure for testing your unknown solution in this week's lab is identical to the procedure which you conducted in Week 1. The only difference is, of course, your Unknown Solution may or may not contain all of the ions which you tested for in Week 1. With that being said, please consider the following scenario:
You enter the lab and obtain an Unknown Solution from the Stockroom. You begin testing the solution through the steps outlined in the flowchart on p. 9 of the Exp 22 document. You first add HCl, and centrifuge your mixture. You observe the formation of a white precipitate in the bottom of the test tube. After pouring off the supernatant liquid, you add hot water to the white precipitate. Upon addition of the hot water, you still have some white precipitate in the bottom of the test tube. You add ammonia, NH3, to the test tube and observe the formation of a gray-black precipitate. Which of the following is the best conclusion to draw at this point? (Choose only one answer.)
a. The unknown solution definitely has Ag+ present.
b. The unknown solution could have Agt present, or Hg22+ present, or BOTH.
c. The unknown solution definitely has Hg22+ present.
d. The Unknown Solution definitely has Pbb present.