How many milligrams of iron are in the sample? See attached file for full problem description.© BrainMass Inc. brainmass.com October 9, 2019, 7:00 pm ad1c9bdddf
First, we have to do is find the molar mass of ferrous ammonium sulfate hexahydrate in order to determine how much actual Fe is in the standard solution.
I calculate it as 296.1 g/mol. Check this out yourself.
Next, we need to find out what percentage the Fe is of the whole compound. Molar mass of Fe is 55.847 g/mol. Therefore,
(55.847/296.1) x 100% = 18.86%
Therefore, if we put in 70.2 mg (0.0702 g) of the compound, we have only 18.86% of that as Fe, right? That means we have:
70.2 mg x 0.1886 = 13.24 mg Fe(II) in the 1 L flask.
Therefore, the concentration of Fe(II) in that flask is:
13.24 mg/1000 mL = 0.01324 mg/ml
Now, we work through the dilutions.
The 1st standard solution results from taking 1 mL of this stock solution and diluting to 100 mL. That's a 1:100 ...
It finds the mass of iron in sample