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Homework Help: Percent of solution

  1. Apr 10, 2008 #1
    [SOLVED] Percent of solution

    1. The problem statement, all variables and given/known data

    Let's say we have 5% glucose of a 10 mL solution. So that would imply that .5 mL of the solution is glucose, but that does not really tell me how much glucose. Is it assumed that the glucose is 1 molar?

    I ask because in one of my bio labs we did a lab where we were given exactly as stated above. Knowing the exact amount of glucose was not needed for the lab, however, I would like to understand this for future use.

    Thanks for any input.
     
  2. jcsd
  3. Apr 10, 2008 #2
  4. Apr 10, 2008 #3
    Yeah, the post above mine tells you exactly what you need to do.
     
  5. Apr 10, 2008 #4
    Okay, let's see if I got this right. Since the solute is H2O, I assume 1 molar H2O.
    Since 1 mole H2O = 18 grams/mole and I use the molarity formula to get grams.
    10mL of H20 or .01L x 1 molar = .01 grams of H20.
    ergo .01g H2O x 5% = 5 x 10^-4 gram glucose, or .0005 gram.
    Is that correct?

    Thanks in advance
     
  6. Apr 10, 2008 #5
    yes now if only someone would help me for christ's sake...
     
  7. Apr 10, 2008 #6
    I wish I could, but as you can see, I am not that good at chem. Thanks for the assist :)
     
  8. Apr 10, 2008 #7

    symbolipoint

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    You probably need to use units of percent weight/volume of solution. The glucose solution is not sensibly prepared as volume of glucose solid per volume of solution.
     
  9. Apr 11, 2008 #8
    So by that you mean, Mass of solute/100 mL solution? So I think that would equate to .5 gram C6H12O6 @ 10mL Does that sound correct?
     
  10. Apr 11, 2008 #9

    symbolipoint

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    That would give you 5 percent weight per volume.
     
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