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Including water in molar mass for molarity?

by mishima
Tags: including, mass, molar, molarity, water
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mishima
#1
Sep27-13, 07:35 AM
P: 343
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?
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mfb
#2
Sep27-13, 10:48 AM
Mentor
P: 11,906
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.
mishima
#3
Sep27-13, 12:58 PM
P: 343
Thanks for that clarification.


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