Ch. 12: Solutions

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Ch. 12 Solutions

• Part 2
• Solution Concentration

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Expressing Concentration
Concentration Description Equation
Percent by mass Mass of solute x 100 Mass of solution
Percent by volume Volume of solute x 100 Volume of solution
Molarity Moles of solute Liter of solution
Molality Moles of solute Kilogram of solvent
Mole Fraction Moles of solute Mol of solute mol of solvent
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2. Percent by Mass

• Equation
• percent by mass mass of solute
• mass of solution
• Example An aquarium must contain 3.6 g NaCl per
  100.0g of water. What is the percent by mass of
  NaCl in the solution?

X 100
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3. Percent by Volume

• Equation
• Percent by volume volume of solute
• volume of solution
• Example What is the percent by volume of ethanol
  in a solution that contains 35mL of ethanol
  dissolved in 115mL of water?

x100
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4. Molarity

• Equation
• Molarity (M) moles of solute
• Liters of solution
• Example A 100.5 mL solution contains 5.10 g of
  glucose (C6H12O6). What is the molarity of this
  solution? The molar mass of glucose is 180.16
  g/mol.

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5. Preparing Molar Solutions

• Step 1 calculate the necessary mass and volume
  needed to make the molar solution required.
• Step 2 measure the mass of solute
• Step 3 place solute into flask
• Step 4 fill solvent to volume needed.
• Example A liter of 2 M NaOH solution contains
  how many grams of NaOH?

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6. Molality

• Equation
• Molality (m) moles of solute
• kilogram of solvent
• Example A student adds 4.5 g of NaCl to 100.0 g
  of water. Calculate the molality of the solution.

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7. Dilutions of Stock Solutions

• M1V1 M2V2
• M1 molarity of stock
• M2 molarity of solution you are making
• V1 volume of stock solution needed
• V2 volume of final solution making