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Mole Fraction

This document provides examples and problems related to calculating concentration in chemistry. It defines and provides examples of calculating mole fraction, molarity, molality, and parts per million (ppm). A series of practice problems is then provided relating to these different concentration units.

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Kim Carson
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208 views13 pages

Mole Fraction

This document provides examples and problems related to calculating concentration in chemistry. It defines and provides examples of calculating mole fraction, molarity, molality, and parts per million (ppm). A series of practice problems is then provided relating to these different concentration units.

Uploaded by

Kim Carson
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PPTX, PDF, TXT or read online on Scribd
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Mole Fraction

Example:
• Compute the mole
fraction of acetone X
(acetone) and of
chloroform (X
chloroform) in a
solution prepared by
mixing 50.0 g each of
acetone (Molar Mass =
58.0) and chloroform
(Molar Mass = 119.5)
Answer the following:
1. 0.100 mole of NaCl is dissolved into 100.0 grams
of pure H2O. What is the mole fraction of NaCl?
2. Calculate the mole fraction of MgCl2 and H2O, if
2 moles of MgCl2 are dissolved in 1000 grams of
water.
3. Calculate the mole fraction of Ethanol and
water, if 3 moles of ethanol are dissolved in 1000
grams of water.
Molarity
Example:
• Calculate the molar
concentration of
the solution that
contains 15 grams
of potassium
hydroxide (KOH) in
225 ml of solution.
(Molar mass of
KOH = 56 g/mol)
Answer the following:
1. Calculate the molar concentration of a
solution that contains 23 g of potassium
hydroxide. KOH in 250 ml of solution. Molar
mass of KOH is 56 g/mol.
2. What is the molarity of a solution that was
prepared by dissolving 14.2 g of NaNO3
(molar mass = 85.0 g/mol) in enough water
to make 350 mL of solution?
3. What is the molarity of a solution that was
prepared by dissolving 82.0 g of CaCl2 (molar mass
= 111.1 g/mol) in enough water to make 812 mL of
solution?
4. What is the molarity of a solution that contains
5.5 g of HCl (molar mass = 36.5 g/mol) dissolved in
enough water to make 250 mL of solution?
Molal Concentration or Molality, m
Example:
•Determine the
molal concentration,
m of a solution that
contains 18 grams of
NaOH in 100 ml of
water. The molar
mass of NaOH is 40
g/mole.
Answer the following:
1. How many grams of solute is present in 0.4 moles
Magnesium hydroxide, Mg(OH)2 in 550 g water,
H2O? The molar mass of Mg(OH)2 is 58 g/mol.
2. Calculate the molality of 200 g of NaOH dissolved
in 150 g of pure water.
3. Calculate the molality of 136 g of HCl dissolved in
25 g of water.
4. Calculate the molality of 1000 g of
H2SO4 dissolved in 5 kg of water.
Parts per Million, ppm
Example:
• A water sample was reported to contain 250 ppm CaCO3.
How many grams of CaCO3 is present in 4 liters of water.
Answer this problem:
1. A commercial pesticide formulation
contains 1.0 g deltametrin in 1L solution.
What is its concentration in ppm?

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