We did an EDTA titration lab with copper sulfate and zinc sulfate, and I got some really confusing results. For moles of EDTA used, I'm getting results that are far larger than the moles of the metal salt that was used. This feels wrong; shouldn't the moles of EDTA be equal to the moles of the metal salt? I've read that the stoichiometric ratio should be 1:1. I'm getting stoichiometric ratios as low as 4.8 (probably 5) and as high as 5.9 (probably six), with one outlier at 9.05 (WHAT?!?!?!)
Is this experimental error? Is there something else going on that I don't know about? I've been trying to figure this out for so long!