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Solution of magnesium sulfate?

  1. Oct 9, 2015 #1
    I would like to make a solution of magnesium sulfate (MgSO4) that is 15%
    magnesium sulfate by mass in water. As magnesium sulfate is sold as epsom salts which is
    MgSO4 7H2O I need a way to calculated the epsom salts required for the required
    magnesium sulfate or 1.24 pounds per gallon of water (Water at 8.35 pounds per gallon).


    I am thinking one goes by atomic weight?
    For MgSO4:
    Mg= 24.3 S= 32.06 Oxgen4= 4* 16 = 64 MgSO4= 120.36

    For 7H2O:
    7H2 = 7*1*2 = 14 7Oxgen = 7* 16 = 112 7H2O= 126.0

    For MgSO4 7H2O= 120.36 + 126.0 = 246.36

    So to get 1.24 pounds of MgSO4: 1.24 * 246.36/120.36 = 2.05 pounds perhaps?

    Thanks in advance.
     
  2. jcsd
  3. Oct 9, 2015 #2

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    Check.
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    Take another swing at the proportion. You'll also want to account for the mass of water you're adding as hydrate.
     
  4. Oct 10, 2015 #3
    Thanks.
    So the ratio of water in epsom salts is: 126.0/246.36 = 51.14 % by weight and
    48.86% MgSO4. So 48.86% of what weight of epsom salts is 1.24 pounds of MgSO4?
    Epsom salts = 1.24/0.4886 = 2.54 pounds ?

    I need to fill my RC blimp envelope with hydrogen.
    Small_Inflated.JPG
     
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