**MUST SOLVE ALL PARTS WITH FULL WORK FOR 5 STARS** A standard solution for Fe 2
ID: 788741 • Letter: #
Question
**MUST SOLVE ALL PARTS WITH FULL WORK FOR 5 STARS**
A standard solution for Fe2+ determination can be prepared from ferrous ammonium sulfate (Fe(NH4)2(SO4)2.6H2O).
1. Calculate the formula weight of ferrous ammonium sulfate. (Units = g/mol)
392.14 (already solved this part)
2. Calculate the mass of Fe in 151 mg of ferrous ammonium sulfate.
3. Calculate the mass of ferrous ammonium sulfate you would need to add to a 2.00 mL volumetric flask to make a solution that is 39 ppm in Fe.
4. Stock solution A is prepared by dissolving 172 mg of ferrous ammonium sulfate in water and diluting to volume in a 500-mL volumetric flask. Calculate the concentration of iron, in ppm, in stock solution A.
5. Stock solution B is prepared by diluting 13.00 mL of stock solution A to 100.00 mL. Calculate the concentration of iron, in ppm, in stock solution B.
Explanation / Answer
ans 2)
mass of fe=
151 mg*(gram molecular mass of fe/formula wt of ferrous ammonium sulfate)
=151*56/392.14(as calculated)
=21.56 mg
ans 3)
39 ppm in fe = 39*151/21.56 ppm of salt
1 ppm =1 part in a million
therefore ther should be 273.144 parts for a million part of solutin
ans4)
conc. of salt is 172/500 gm/lt
we multiply this by the factor 56/392.14 to obtain the conc of fe
ans5)
thw conc of fe in salt sol b be comes 13/100 of its conc in salt sool a as it is diluted
msg me if there is any doubt
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