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Homework Help: Emperical Formula for hydrate

  1. Dec 11, 2008 #1
    I have a lab in which I need to devise my own procedure for calculating the emperical formula of magnesium sulfate hydrate. I have done some research and found out that the simplest way to find it would be through evaporating the water off the hydrate, calculating the masses of the anyhydrous salt and water separately and then, dividing the mass values to find the simple formula ratio.

    So My question is: Is it possible to use another method beside evaporating the water in order to find the Emperical Formula? Can I use a precipitate method to calculate the Emperical Formula?(As in I add some of the magnesium sulfate hydrate into water and then I mix it with another solution that will then form a precipitate.)

    My idea is that I can calculate the mass of the precipitate I formed, filter it, dry it, and then use stochiometry to at least find the mass of the anhydrous magnesium sulfate. However, I'm curious as to how I would find then calculate the mass of the water molecules. If you have any suggestions at all, please reply

    Thanks for your help
  2. jcsd
  3. Dec 12, 2008 #2


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    Staff: Mentor

    If you know initial mass of the sample, and amount of MgSO4 in it, you can calculate mass of water, don't you?

    You first idea was OK, although sometimes it won't work. You have to be sure if your salt didn't decompose on roasting.
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