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March 30, 2017

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Describe how you would prepare 250.0 mL of a 0.500 M solution of NaCl by using apparatus found in a chemistry lab.

  • chem help asap - ,

    did you try putting it in a 600mL beaker?

  • chem help asap - ,

    no

  • chem help asap - ,

    The definition of molarity is
    M = #mols/Liter of solution.
    If you want to do this by math (instead of reasoning), you first plug in 0.5 for M and 0.250 for L and calculate #moles.
    0.5=moles/0.250 L
    moles NaCl = 0.5 x 0.250 = 0.125 moles.
    1 mole NaCl = approximately 58.5 grams. So 0.125 moles NaCl is ......

    Or by reasoning, we want 0.5 mole for 0.5 M in 1 L and divide that by 4 for only 1/4 of a liter (250 mL). So we want 1/4 of 1/2 = 1/8 of a mole (or 0.125 mol).

    But this isn't the tricky part. The tricky part is telling the prof HOW to prepare the solution. You will want to take 1/8 mole NaCl (about 7 grams or so), place it in a 250 mL volumetric flask, add a little water, swirl until all of the NaCl is dissolved, then make to the mark with water. That will prepare 0.5 M solution in a 250 mL volumetric flask. (Note that I DID NOT say to add about 7 grams NaCl to 250 mL water.).

  • chem help asap - ,

    write the steps something like this

  • chem help asap - ,

    1. Place 0.125 moles NaCl (7.305 grams) in a 250 mL volumetric flask, add some water, swirl to dissolve all of the NaCl, then make to the mark with water. You PROBABLY should round the 7.305 g to 7.31 grams.

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