Physics and Astronomy

Chemical Detective
Objective Determine which two ions produce precipitates and deduce their formulae.
Participants Teams of up to six.
Materials You will have seven numbered solutions to combine two at a time. Each solution contains two ions, one positive, one negative. The ions are given letters and charges. You are not told the names of the ions. Each team will be given two copies of a grid sheet, and one sheet of clear plastic.

1. Use single drops of solution. Be careful not to contaminate the solutions by touching the top of the dropper in another droplet.
2. Allow at least one minute to pass before recording your results. Remembering that positive ions combine with negative ions, and that a compound is electrically neutral ( charges must balance ) deduce which combination is actually the precipitate.
3. When you have finished please assure that the tops are secure on all dropper bottles and that the acetate sheets are wiped dry with paper towel provided.


The team identifying the most ions will be the winner. If there are ties, the fastest team will win.

Source Technical University of Nova Scotia.

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