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Homework Help: Chemistry % composition question

  1. Sep 19, 2010 #1
    1. The problem statement, all variables and given/known data

    A certain metal hydroxide, M(OH)2, contains 32.8% oxygen by mass. What is the identity of the metal M?

    2. Relevant equations
    O = 16.00 g x2
    H = 1.008 g x2

    3. The attempt at a solution

    I thought that 1g = 1% of the mass because there are 32g of O and it composed of 32.8% of O. So then I thought it would be around 2% of H. Then I added 32.8% + 2% and subtracted it from 100%. This was supposely my answer. I thought it was Zinc and it was wrong.
  2. jcsd
  3. Sep 19, 2010 #2


    User Avatar

    Staff: Mentor

    You are not completely off, but you have to do your calculations using exact value of the oxygen percentage.

  4. Sep 19, 2010 #3
    oh thanks...i got the right answer now
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