Originally posted by Affinity
it's not reliable because fertillisers are usually heterogenous(unless it's a just a single compound, without insoluble solids), and the sulphate content varies from each sample taken.
The HCl would stop the phosphates precipitating out (check conquering chem if you wanna know why - the ion tests section). Comparing your value with the given one wouldn't be reliability, it would be validity; you could get the same value every time (not that you would, as Affinity explained), but it'd be way out.hmmm... good point... as far as i know, we chuck acid in to get rid of the carbonates... but yeah, phosphates?
let us suppose they do not exist.
SHIT I FORGOT TO MENTION YOU CAN CHECK RELIABILITY BY CHECKING THE BACK INFORMATION PANEL OF YOUR FERTILISER!!!! >.<
I know! I agree...I was just posting what my teacher told me about reliability and validity...it was a pretty dodge question. I concentrated on validity anyway so hopefully I'll get some sympathy marks or something!Originally posted by Frigid
that's all well and good, but as i said before, in the scope of the sulfate prac, there isn't much to be said of reliability:
yes, it's very reliable; reliable for repeated INACCURATE results!!!
everyone repeat with me: gravimetric analysis suxxorz.