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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: 123hello123 on April 21, 2012, 08:47:43 PM

Title: Given Fe2(SO4)3 2%(w/w) , does that mean this is the %(w/w) of two Fe?
Post by: 123hello123 on April 21, 2012, 08:47:43 PM

If it does, does that mean my results (about 3.7) is correct (this is the amount of Fe only, not Fe2(SO4)3)- due to some spillage, I know that it should be under 2%(w/w).

Title: Re: Given Fe2(SO4)3 2%(w/w) , does that mean this is the %(w/w) of two Fe?
Post by: Arkcon on April 21, 2012, 09:20:10 PM

If the label doesn't say x% Fe, then it means the sample is 2% Fe₂(SO₄)₃ and 98% dirt or powdered stone or something.  I don't know how you've computed the Fe amount, but you have to compensate as above.

Title: Re: Given Fe2(SO4)3 2%(w/w) , does that mean this is the %(w/w) of two Fe?
Post by: 123hello123 on April 21, 2012, 09:26:02 PM

I'm a little confused as to what you mean. I wanted to know, with 2%(w/w) Fe2(SO4)3 in mind, if the amount of Fe that I calculated is sensible? I used UV-vis spec. to get my raw data.

Title: Re: Given Fe2(SO4)3 2%(w/w) , does that mean this is the %(w/w) of two Fe?
Post by: Arkcon on April 21, 2012, 10:51:33 PM

Ah.  Sorry, I got it backwards.  OK, experimentally, you've determined the Fe concentration is 2%. Now you want to report % Fe₂(SO₄)₃?  Yeah, you will have to convert that.