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Homework Help: Finding the Molarity of the Reactant

  1. Jun 9, 2012 #1
    1. The problem statement, all variables and given/known data
    96 grams of Iron(III)Chloride is dissolved in water to give 300ml of solution. What is the Molarity of Iron(III)Chloride? What is the Molarity of just the Chloride?

    2. Relevant equations
    FeCl3 + H2O → Fe+3 + 3Cl-

    3. The attempt at a solution
    96g FeCl3 X (1 mol FeCl3 / 162.2g FeCl3) = .59 mol FeCl3

    Then I found the molarity of the solution.
    .59 mol FeCl3 / .3L solution ≈ 2M solution.

    I'm just confused as to where I go from here to find the molarity of the FeCl3 and then the Cl. Any help would be much appreciated, thanks!

    Edit: Did some more tinkering.

    .59 mol FeCl3 X (3 mol Cl- / 1 mol FeCl3) = 1.77 mol Cl-

    M Cl-= 1.77 mol Cl- / .300 L
    M Cl- = 5.9M
    Last edited: Jun 9, 2012
  2. jcsd
  3. Jun 9, 2012 #2
    Your working is correct :smile:
  4. Jun 10, 2012 #3


    User Avatar

    Staff: Mentor

    There is one small problem. Iron(III) chloride as a solid is usually present in the form of hexahydrate. Not knowing the context in which the question was asked it is hard to say if your molar mass is right or not.
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