Chemistry Ch 16

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  1. The compositions of the solvent and the solute determine whether a substance will dissolve. 
    What makes it dissolve?
    Stirring (agitation), temperature, and the surface area of the dissolving particles determine how fast the substance will dissolve.
  2. It's important to realize, however, that agitation (stirring or shaking) affects only the _____
    • rate at which a solid solute dissolves.
    • It does not influence the amount of solute that will dissolve.
  3. The more surface area of the solute that is exposed, the faster the _______.
    rate of dissolving
  4. If you add 36.0 g of sodium chloride to 100 g of water at 25°C, all of the 36.0 g of salt dissolves. But if you add one more gram of salt and stir, no matter how vigorously or for how long, _______________
    only 0.2 g of the last portion will dissolve.
  5. Temperature affects the solubility of solid, liquid, and gaseous solutes in a solvent; both _______ __ __________ affect the solubility of gaseous solutes.
    temperature and pressure
  6. Gas solubility increases as the partial pressure of the gas above the solution ______.
  7. Molarity (M) is the number of moles of solute dissolved in one liter of solution. To calculate the molarity of a solution, divide
    the moles of solute by the volume of the solution.
  8. Diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solute in solution does not change.
  9. Moles of solute = M1 × V1 =
    M2 × V2
  10. The concentration of a solution in percent can be expressed in two ways: as the ratio of the volume of the solute to the volume of the solution or as the ratio of the mass of the solute to the mass of the solution.
  11. Three important colligative properties of solutions are vapor-pressure lowering, boiling-point elevation, and freezing-point depression.
  12. The decrease in a solution’s vapor pressure is proportional to the number of particles the solute makes in solution
  13. The freezing point of a solution is lower than the freezing point of the .
    pure solvent
  14. The magnitude of the freezing-point depression is proportional to the number of solute particles dissolved in the solvent and does not depend upon their identity.
  15. The magnitude of the boiling-point elevation is proportional to the number of solute particles dissolved in the solvent.
  16. The unit molality and mole fractions are two additional ways in which chemists express the concentration of a solution. The unit molality (m) is the number of moles of solute dissolved in 1 kilogram (1000 g) of solvent. Molality is also known as molal concentration.
  17. The mole fraction of a solute in a solution is the ratio of the moles of that solute to the total number of moles of solvent and solute
  18. The magnitudes of the freezing-point depression (ΔTf) and the boiling-point elevation (ΔTb) of a solution are directly proportional to the molal concentration (m), when the solute is molecular, not ionic.
  19. ΔTf = Kf × m
    ΔTb = Kb × m
Card Set
Chemistry Ch 16
Chemistry Ch 16
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