Anonymous
Anonymous asked in Science & MathematicsChemistry · 4 weeks ago

I can't figure out this Chemistry question. Can someone help?

How many grams of Na2SO4 must be dissolved in 2000.0 mL of solution to produce a solution that is 4.0-M?

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  • david
    Lv 7
    4 weeks ago

    Roger's answer is probably correct, but I'm going to try to explain more.

      ...  most of these problems start by doing the molar mass ....  I will call that k (because M is used for something else.

      M -- is molarity or concentration in moles / liters

      ===  now start canceling things

      (4.0moles/1Liter)  X (1L/1000mL) X (2000mL) X (k g/mole)

      ...  sub the molar mass in place of k .. then just use a calculator  ..  --- good luck.

    • david
      Lv 7
      4 weeks agoReport

      Probably because I was not taught the unit-factor method in HS.  We did every problem using equations (gas laws) or by proportions. --  My older brother had a Schaum's outline of Chem. which I inhereted and everythng was done using proportions.  For me, and some others, proportions MAKE SENSE.

  • 4 weeks ago

    (2.0000 L) x (4.0 mol/L) x (142.0421 g Na2SO4/mol) = 1136.34 g = 1100 g Na2SO4

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