[needhelp22]

We are doing a lab to figure out what cations are in a solution. The possibilities are

Al3+, Ca2+, Cu2+, Fe3+, Pb2+, Mg2+, K+, Ag+, Na+, Zn2+

Ive gotten down the procedures to test for most of the..they are...

Test for Fe3+
1.   Add Thioacetamide (sulfide ions), heat, and concentrated ammonia (to make solution basic. If a precipitate forms, then Fe3+ is present in solution.
Test for Ca2+
2.   Add sulfate to see if a precipitate form. If one does, Ca2+ has a possibility to be present in the solution. To confirm this, add OH- to the solution to see if no precipitate forms. If none does, then Ca2+ is present in the solution.
Test for Pb2+
3.   If sulfate ions created a precipitate and OH- performed a precipitate then you have Pb2+ in your solution. Add chloride ion to the solution to see if precipitate forms just as precaution. One should form with the reaction with Pb2+.
Test for Ag+
4.   Add chloride ions to the solution to see if a precipitate formed (already done). Add sulfate to the solution to see if precipitate forms (already done). If precipitate forms with just chloride ions but not with sulfate ions, then Ag+ is present in the solution.
Test for Mg2+
5.   If precipitate does not form with sulfate or chloride ions, add fluoride ions. If a precipitate forms, then Mg2+ is present.
Test for Cu2+
6.   Add Thioacetamide (sulfide ions), HCl (to make solution acidic), and heat. If a black precipitate forms, then Cu2+ is present in solution.
Test for Al3+
7.   ?
Test for Zn2+
8.   ?
Test for Na+ or K+ (only one can be in solution)
9.   Perform a flame test, if a lavender color is the result, K+ is present. If a yellow color is the result, Na+ is present

Only problems im having are to test for Zinc or Aluminum, what are some tests i can run for them?

Also my teacher said we dont have Thioacetamide at school, what is something else i can use to produce sulfur ions?

[needhelp22]

anyone?

[Astrokel]

hey!

maybe you can try ammonia. Zn2+ forms white ppt when NH3 is added but it dissolves when there is excess NH3. However Al3+ and Pb2+ doesn't.

http://en.wikipedia.org/wiki/Sulfide  (Source of sulphides)

http://www.bpreid.com/applets/cations.html (Fun link!, click on the lab bench and try out with the reaction section for guides)

http://home.clara.net/rod.beavon/cations.htm (Simple tests)

http://faculty.coloradomtn.edu/jeschofnig/class/class_jeschof/ch2-lb8.htm (More tests, worth looking)

have fun!