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Calculate the concentration in g L^-1 and the molarity of each compound.Each 200 mL of...

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jesicatran | Student, Grade 9 | Honors

Posted January 20, 2012 at 9:22 AM via web

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Calculate the concentration in g L^-1 and the molarity of each compound.

Each 200 mL of an electrolyte solution designed for treating dehydration contains 0.47 g of sodium chloride (NaCl), 0.30 g of potassium chloride (KCl) and 3.56g of glucose (C6H12O6).

(The answer for the concentration in g L^-1 17.8 g L^-1 and the molarity is 0.9989 M)

If this is considered as me asking 2 questions at once, I just thought that because them two are questioned in my textbook in one sentence, I thought it would be okay for me to do so.

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ndnordic | High School Teacher | (Level 2) Associate Educator

Posted January 20, 2012 at 12:01 PM (Answer #1)

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Since molarity is defined as moles per liter, you need to first determine how many grams of each compound you would have in 1 liter.  This would be 5 times as much as in 200 mL. This calculation will also give you the concentration in grams/liter.

Second, find the formula mass of each of the three compounds:

formula mass of NaCl = atomic mass of Na + atomic mass of Cl

formula mass of KCl = atomic mass of K + atomic mass of Cl

formula mass of glucose = atomic mass of C * 6 + atomic mass of hydrogen * 12 + atomic mass of O * 6.

Now you can divide the actual mass of each compound by its formula mass to find the molarity of each compound.

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