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Including water in molar mass for molarity?

  1. Sep 27, 2013 #1
    Hi, lets say I need 60 mL of a 1M solution of potassium sodium tartrate, I am looking for how many grams to measure out of my stock. So I need to convert mol to grams using molar mass. Do I use the full formula weight that includes water KNaC4H4O6*4H2O, or simply the KNaC4H4O6?
  2. jcsd
  3. Sep 27, 2013 #2


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    You need a specific number of molecules of your substance. If every molecule carries 4 H2O around, you have to take more mass to get the same number of molecules.
    Use the full formula weight, including H2O.
  4. Sep 27, 2013 #3
    Thanks for that clarification.
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