Warning!

The use of chromium (VI) compounds is not allowed in many high schools, because of concerns about its carcinogenicity.   Because of the small amount used by students to carry out this lab, the risk to them is small; however, disposal of waste materials may pose a problem.  For this reason, teachers should be extremely cautious in having students carry out this procedure.   Consult your local school safety guidelines before doing so.

A set of photographs showing the various results are included for reference, so that you need not actually physically handle the chemicals.