In Chemistry today we did a practical to determine the amount of Iron(II) in dried thyme. Partway through the experiment method, it instructed us to put some of a solution of Sulphuric acid (1moldm^-3) and thyme into a plastic beaker. It struck me as odd that the method specified the material, as it's not something I've come across in the two years of the course. I wondered whether there was any basis for material specification in this case, or whether glass versus plastic is arbitrary. Are there any circumstances in which plastic only should be used versus glass, or vice versa?

Hm, maybe it has to do with iron. If you're going to precipitate it out or something, you might end up staining your glass, and also I think that the iron wouldn't stick as good to the plastic.

 

For an example where you can't use glass is hydrofluoric acid, HF, which dissolves glass. It's also really nasty and you probably won't ever have need to use any.

Most glass has iron in it, though I doubt you would be able to measure the amount extracted with the kit in a school ( or even undergraduate ) lab.

Brilliant, thank you so much for your prompt reply!