Molarity

1
Molarity

• Molarity grams / molar mass / Liters
• Liters grams / molar mass/ Molarity
• Grams Molarity x Liters x molar mass

2
Molarity

• The higher the number the more concentrated
• Which solution is more concentrated?
• 1 M 3.5 M
• 0.5 M 2.0 M

3
Molarity Review

• What is the molarity of a solution containing 400
  grams of lithium chloride in 500 mL of water?

4
Molarity Review

• If you a 4.5 M solution with 35 g of NaCl, how
  many liters do you have?

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Molarity Review

• You need to prepare 800 mL of a 1.5 M solution of
  magnesium oxide. How many grams do you need?

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Dilutions Section 15.2

• Dilute add more solvent
• Moles of solute do not change. Therefore
• moles of solute before moles of solute after
• M1V1 M2V2

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Dilutions

• Volume does not have to be in Liters
• Each side the equation must have the SAME VOLUME
  UNITS
• Molarity x mL Molarity x mL
• or
• Molarity x L Molarity x L

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Dilutions

• Stock solution
• The original solution that gets diluted to get
  the desired concentration of the new solution

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M1V1 M2V2

• 1. How much stock solution do I need to prepare
  500 mL of a new solution with a concentration of
  4.5 M if the stock solution is 11.6 M?

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M1V1 M2V2

• 2. What volume of a 3 M KI solution would you
  use to make 0.3 L of a 1.25 M KI solution?

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M1V1 M2V2

• 3. How many milliliters of a 5 M H2SO4 solution
  would you need to prepare 100 mL of a 0.25 M
  solution?

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M1V1 M2V2

• 4. If you dilute 20 mL of a 3.5 M solutions to
  make 100 mL solution, what is the molarity of the
  dilute solution?

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M1V1 M2V2

• 5. What is the molarity if 1279 g of K3PO4 is
  dissolved in 4 L of water?

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• 5. What is the molarity if 1279 g of K3PO4 is
  dissolved in 4 L of water?

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M1V1 M2V2

• 6. If you dilute 50 mL of a 6 M solution to make
  200 mL solution, what is the molarity of the new
  solution?

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• 7. How many grams of magnesium sulfate would be
  dissolved in 1 L to make a 0.3 M solution?

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• 8. If 0.65 g of a gas dissolves in 1 L of water
  at 2 atmospheres of pressure, how much will
  dissolve at 22 atmospheres of pressure?

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15.3 Colligative Properties

• Colligative depends on the collection
• Properties that depend on how many solute
  particles are present
• Does NOT depend on identity of solute

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Vapor Pressure Lowering

• Vapor pressure pressure created by particles
  going from liquid to gas inside a closed
  container
• If you add solute, not as much solvent can escape
  into the gas phase

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Boiling Point Elevation

• Boiling liquid to gas
• The more solute added to a solution, the lower
  the vapor pressure and therefore the higher the
  boiling point

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• A solvent has a boiling point of 200C. When 10
  grams of salt is dissolved in the solvent, what
  is the most likely new boiling point?
• a. 210C
• b. 200C
• c. 190C

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Freezing Point Depression

• Freezing solvent particles moving into solid
  crystalline form
• Solute gets in the way of making crystals
  preventing the solvent from freezing. Lower
  temperature is needed to freeze

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• A solvent has a freezing point of 10C. What is
  the most likely freezing point if 5 grams of salt
  is mixed with the solvent?
• a. 5C
• b. 10C
• c. 15C

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Osmotic Pressure Increase

• Osmosis-movement of water from low to high
  concentration. Goal is to balance the
  concentrations
• Osmotic Pressure Increases