2 SA

    Cards (57)

    • What are the two common units of concentration discussed in this lesson?
      Molarity and molality
    • Why is molarity commonly used in laboratories and hospitals?
      Because it is easy to calculate
    • When is molality preferred over molarity?
      When accurate concentration is needed amid temperature changes
    • What is the definition of molarity?
      • Number of moles of solute
      • Dissolved in one liter of solution
    • What is the unit for molarity?
      M
    • How can molarity be expressed in terms of volume?
      As mol/L
    • Why is molarity easy to use for aqueous solutions?
      Because the solute is usually solid
    • What is a convenient use of molarity?
      Converting moles to volume in liters
    • What is a limitation of molarity regarding temperature?
      Molarity is susceptible to temperature changes
    • What causes deviations in molarity due to temperature changes?
      Differences in intermolecular forces
    • What is the definition of molality?
      • Number of moles of solute
      • Dissolved in one kilogram of solvent
    • What is the unit for molality?

      m
    • Why is molality independent of temperature changes?
      Mass does not change with temperature
    • What is true about masses in relation to intermolecular forces?
      Masses are additive regardless of forces
    • What is the difference in the denominator for molarity and molality?
      Molarity uses volume in liters, molality uses mass in kilograms
    • What is the molarity of a solution with 15 moles of glucose in 2 L?
      7.5 M
    • What is the molality of a solution with 8 moles of rock salt in 20 kg of water?
      0.4 m
    • How many moles of sodium phosphate are needed for a 2.5 molal solution in 30 kg of water?
      75 moles
    • How many moles of potassium acetate are needed for a 1.5 molar solution in 0.250 L?
      0.375 moles
    • How many grams of benzoic acid are needed for a 2.5 M solution in 500 mL?
      152.65 grams
    • How many grams of potassium hydrogen phthalate are needed for a 1.5 m solution in 500 g of water?
      102.11 grams
    • What are the collective groups of units of concentration?
      • Percentage by mass
      • Percentage by volume
      • Percentage by mass per volume
      • Molarity
      • Molality
      • Normality
    • What are the formulas for molarity and molality?
      • Molarity: M=M =nsolutevsolution \frac{n_{solute}}{v_{solution}}
      • Molality: m=m =nsolutemsolvent \frac{n_{solute}}{m_{solvent}}
    • What factors are needed to convert molarity to molality?
      Density of the solution and temperature
    • Who are the authors of the referenced textbooks?
      Chang, Goldsby, Handwerker, Hawe, Petrucci, Silberberg
    • What is one way to express the concentration of solutions?
      Parts per million (ppm)
    • What will you learn in this lesson?
      About mole fraction, ppm, and ppb
    • What is a mole fraction?
      Ratio of moles of a substance to total moles
    • How is mole fraction denoted?
      By the Greek letter chi (𝜒)
    • What is the nature of mole fraction as a unit?
      It is unitless
    • What should the sum of mole fractions of all components equal?
      It should equal 1
    • What is the mole fraction of glucose in a solution with 0.50 moles of glucose and 2.50 moles of water?
      0.17
    • What is the mole fraction of NaCl in a solution with 1.25 moles of NaCl and 3.75 moles of water?
      0.25
    • What is the mole fraction of ethanol in a solution with 25 g ethanol and 75 g water?
      0.12
    • What is the mole fraction of KNO<sub>3</sub> in a solution with 10 g KNO<sub>3</sub> and 50 g water?
      0.10
    • What is the mole fraction of CaCl<sub>2</sub> in a solution with 15 g of CaCl<sub>2</sub> in 50.0 mL of water?
      0.046
    • What is the mole fraction of naphthalene in a solution with 4.75 g of naphthalene in 250.0 mL of benzene?
      0.018
    • What does ppm stand for?
      Parts per million
    • What does parts per million refer to?
      A portion out of one million
    • Can ppm be calculated by milligrams solute per milligram solution multiplied by 10610^6?

      Yes, it can be calculated this way
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