Thank you for your question. The members of the ASSIST team have no direct experience with this particular activity. We are, however, very concerned about the potential use of potassium dichromate in a Year 9 activity because of its extremely hazardous nature. It is highly toxic, a known sensitiser, and has evidence of carcinogenic and teratogenic effects (1). In a school science setting, potassium dichromate use would normally be limited to senior chemistry practicals and be under strict supervision.
If the purpose of the activity is to demonstrate a chemical cell generating a small electric current, then we strongly recommend that another activity using safer chemicals be substituted. There are many possibilities here including
- Al and Cu electrodes with salt water solution
- Cu and Zn electrodes with copper & zinc sulfate solution
- Fruit batteries using lemons, kiwi fruit
A web search on electrochemistry experiments will locate useful websites such as those below which include such activities:
- https://web.archive.org/web/20171226234654/http://www.funsci.com/fun3_en...(April 2018; The original site no longer exists. This copy provided by the Internet Archive)
Since your question is about making chemical cells, we hope that this answer has helped.