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Homework Help: Concentration Trouble

  1. Feb 7, 2005 #1

    DB

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    What mass of solute do you need to make 50 ml of a 20 g/L solution?

    [tex]\frac{20_g}{1000_{ml}}=\frac{x_{g}}{50_{ml}}[/tex]

    20 g/L = 1 g/50ml

    Answer: 1 g

    How many grams of solute are there in 300 g of .50% NaCl solution

    [tex].50%=\frac{x_g}{300_{ml}} * 100[/tex]
    [tex].005%=\frac{x_g}{300_{ml}}[/tex]
    x=1.5 grams

    How'd I do?

    Thanks
     
  2. jcsd
  3. Feb 7, 2005 #2

    DB

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    lol 1 more

    How many grams of solute are needed to prepare 250 ml of a 10 mol/L HCl solution

    1 mol of HCl=36 grams (Cl=35 + H=1)

    [tex]\frac{10_{mol}}{1000_{ml}}=\frac{x_{mol}}{250_{ml}}[/tex]

    2.5 mol x 36 = 90 grams

    ?
     
  4. Feb 7, 2005 #3

    dextercioby

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    The second is okay.I wish you had put the zero before the dot,as it's highly misleading... :grumpy:

    The last is okay.

    Daniel.
     
  5. Feb 7, 2005 #4

    DB

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    thanks, sorry bout the zero
     
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