Solutions Part II: Units of Concentration (loosely from Jespersen Chap. 13 Sec 5)

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SolutionsPart II Units of Concentration(loose
ly from Jespersen Chap. 13 Sec 5)

• Dr. C. Yau
• Spring 2014

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Units of Concentration
Molarity (M) Molality (m) Mole fraction
mole Mass , ppt, ppm, ppb
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Percent by Mass
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What does 15 w/w mean? w/w means 15 w/w
means 1 ppt means....? 15 ppb means....?
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Example 13.2 p.598
Please dont waste time copying the question.
You can get it later from your textbook. Seawater
is typically 3.5 sea salt and has a density of
about 1.03 g mL-1. How many grams of sea salt
would be needed to prepare enough seawater
solution to completely fill a 62.5 L aquarium?
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Molality vs Molarity
Know WHEN m is almost the same as M...under what
conditions? If we have a very dilute solution,
such as 0.0005 M which is In such a solution,
there is very little solute present, therefore 1
L soln 1 L water.
Ans. m M for very dilute solutions
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Ex 13.3 p.599
An experiment calls for a 0.150 m solution of
sodium chloride in water. How many grams of NaCl
would have to be dissolved in 500.0 g of water to
prepare a solution of this molality?
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Interconversion of Units of Concentration
Example 13.4 p. 601 What is the molality of 10.0
w/w aq NaCl?
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Example 13.5 p. 602

• A certain supply of conc hydrochloric acid has a
  concentration of 36.0 HCl. The density of the
  solution is 1.19 g mL-1. Calculate the molar
  concentration of HCl.

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p.629 13.48

• What is the molality of NaCl in a solution that
  is 3.000 M NaCl, with a density of
• 1.07 g mL-1?
• Be sure to learn how to convert between different
  units of concentration.
• Practice Exer 6-8 on p.600
• Exer 9 10 on p.602
• Exer 11 12 on p.603
• Do as many as possible p.629 48-57.