Full Lab Manual
Introduction & Goals
Chemistry & Background
In Your Write-up
1. Describe the process of washing a precipitate. Why must this be done carefully and completely? How will you test the pH of the sample in your test tube? What are the steps for using a centrifuge?
2. How could you separate each of these pairs?:
(i) Ag+(aq), Cu+2(aq)
(ii) AgCl(s), CuC12(s)
(iii) AgCl(s), PbC12(s)
(iv) Ag+(aq), Fe2+(aq)
3. Construct a logical flowchart for the analysis of an unknown mixture of cations. Include balanced chemical equations and confirmation tests for each ion. Show clearly what is contained in the precipitate and centrifugate for each step of the analysis. A partial flowchart is given below, to help you get started.
4. Use the web applet Qualitative Analysis of Cations to test a web-based unknown sample. Practice with known samples and unknowns that you can reveal before trying a "true unknown". Follow the procedure and use your flowchart from prelab problem 3. In your lab notebook, record the code number of your "true unknown" and its identity for your TA to grade. Like all prelab problems, this one should be done independently, not in collaboration with a lab partner or friend. You can access the applet by clicking on the link below.
Qualitative Analysis of Cations Applet
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