Question

Stock solution A is prepared by dissolving 165.1 mg of ferrousammonium sulfate in water and diluting to volume in a 500-mLvolumetric flask. Calculate the concentration of iron, in ppm, instock solution A.

I tried this first: I took the mg of ferrous ammonium sulfate andconverted it to grams then divided by the molecular weight (392.14g/mol) giving me moles of FAS. Then I multiplied by 0.5 L given methe molarity of the FAS solution. I then multiplied by 1000 and Imultiplied by the molecular weight of iron (55.847 g/mol). I got11.756 ppm but this is incorrect.