Fern Hi Fern, I’ve just had two weeks of testing and tweaking this so you’re in luck :]
I tried acetic acid, copper sulfate, lead acetate, lead nitrate, iron sulfate and zinc sulfate as inhibitors.
Copper sulfate was the best and I found it worked best using 10 concentrations from 0.01M up to 0.1M (0.01M, 0.02M, 0.03M, 0.04M, etc). Each group used 5 concentrations, 5 used the even numbers and 5 used the odd. I used 5% hydrogen peroxide as the substrate as I found that worked best. 1% catalase was used. I’ll post a video of the results if I can.
Lead nitrate worked as well at the same concentrations. You’ll find that copper sulfate is a much better inhibitor but that makes for a good comparison.
The rest of the inhibitors were disappointing. I found lead acetate actually catalysed the breakdown of hydrogen peroxide (strangely enough, I also observed this with copper sulfate at concentrations above 0.5M). I didn’t observe any inhibiton of catalase with the iron and zinc sulfates. I tried acetic acid and that worked well surprisingly. Unfortunately it worked too well and even with a very weak solution it seemed to inhibit the catalase.
Overall, it seems copper sulfate and lead nitrate worked best so I’d stick to those.
