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Homework Help: Solution concentrations

  1. Oct 1, 2009 #1
    1. The problem statement, all variables and given/known data

    a. the initial Fe3+ concentration of all of the solutions?
    b. the initial SCN1- concentrations of Solutions #1A thru #5A?
    c. the final concentration of FeSCN2+ in Solution #1A?

    2. Relevant equations
    The first column is the solution number, the second column is the volume of .100M Fe^3+, the third column is the volume of 5.00e-4M SCN^1-, the fourth column is the volume of water, and the fifth column is the total volume. All volumes are in units of mL.

    1A 1.00 1.00 4.00 6.00
    2A 1.00 1.50 3.50 6.00
    3A 1.00 2.00 3.00 6.00
    4A 1.00 2.50 2.50 6.00
    5A 1.00 3.00 2.00 6.00

    3. The attempt at a solution

    For part a., I tried multiplying the given .100M by .001L to get .000100M. This, however, is incorrect according to my online assignment.

    For part b., I did the same thing but with the SCN^1-. I multiplied the 5.00e-4M by the volume in mL. So for solution #1A, I did (5.00e-4M)*(.001L) and got .000000500M. This too is incorrect on both in both respects.

    Part c is the same deal.

    If anyone could help me with part a and maybe one from part b, I could do the rest. Any help is much appreciated.
  2. jcsd
  3. Oct 1, 2009 #2


    User Avatar

    Staff: Mentor

    0.100M*0.001L is not 0.0001M, pay attention to units.

  4. Oct 1, 2009 #3
    Okay. I'll rephrase what I think I should do. I think I need to use the formula C1V1=C2V2. Given the concentration of Fe^3+ and the volume of Fe^3+, what should I use for V2. Should it be the volume of Fe^3+ plus the volume of water. If that is the case they wouldn't all be the same since the volume of water differs for solutions 1-5, however, the question asks for one number.
  5. Oct 1, 2009 #4
    Figured it out.....nevermind
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