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Density and concentration

  1. Sep 27, 2015 #1
    If 50kg of salt is mixed with 100 kg of water to form a 1500kg/m^3 solution, can I find the concentration of salt by subtracting the density of water which is 1000kg/m^3, or do I have to equate it like this: 50/((50+100)/1500)=500kg/m^3 ? Is the volume of salt negligible so that the volume of solution equals the volume of water?
     
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  3. Sep 27, 2015 #2

    SteamKing

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    The concentration of a solution can be defined in several different ways. Here are some of them:

    https://www.chem.purdue.edu/gchelp/howtosolveit/Solutions/concentrations.html

    The density of most salts is often greater than that of water. For common table salt, NaCl, its density is 2.17 g/cc (water = 1.0 g/cc)

    https://en.wikipedia.org/wiki/Sodium_chloride

    Your example solution has a final density of 1500 kg/m3. Since you know that 50 kg of salt is mixed with 100 kg of water, you should be able to figure out the volume of solution created, since the total mass of solution must equal the total mass of the stuff being mixed together.

    For more information about solutions:

    https://en.wikipedia.org/wiki/Solution
     
  4. Sep 27, 2015 #3

    Borek

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    How do you know that's the density of the solution produced?
     
  5. Sep 27, 2015 #4

    SteamKing

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    You don't, but that's what the OP said.
     
  6. Sep 27, 2015 #5

    Borek

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    I wonder if OP doesn't think density is in some strange way additive.
     
  7. Sep 27, 2015 #6

    Bystander

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    The solution process is magical, partial molal volumes of solutes are all zero.
     
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