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Finding Concentration of a Standard Solution using % purity ?

  1. Feb 2, 2013 #1
    1. The problem statement, all variables and given/known data

    I need to know the concentration in ppm of a standard Fe2+ solution. (diluted)
    Here is the data I have.
    I have 0.1964 g of Fe solution
    the purity is 99.7%

    The original solution was the above # of g in 250ml water.
    10ml of this was then pipetted into a 100ml volumetric flask and diluted.
    I have to find the concentration in ppm of this diluted solution using the info from the starting solution.


    2. Relevant equations

    Don't think there are any. Just need logic to figure it out, of which I am limited in.

    3. The attempt at a solution

    196.4mg/0.250L
    =785.6 mg/L
    *(10ml/100ml)
    =78.56 ppm

    This is what I have, but I don't think it's right because 78.56 ppm is not in the range of the spectrometer we used. Also, I didn't use the 99.7% purity anywhere.

    Thanks.
     
  2. jcsd
  3. Feb 3, 2013 #2

    epenguin

    User Avatar
    Homework Helper
    Gold Member

    Actually mg/ml is ppm - work it out.

    Then you'll have the ppm of the stuff you put in the flask.

    But only 99.7% of the stuff you put there is the Fe you are interested in.
    So how many ppm is that?

    Simples.

    Assuming you have reported the question entirely because I am a bit puzzled about what ppm of "Fe" means, (you didn't weigh out iron filings, does your source give some convention?)
     
    Last edited: Feb 3, 2013
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