CHEM 001B Lecture Notes - Lecture 16: Freezing-Point Depression, Boiling-Point Elevation, Colligative Properties
Document Summary
For mixtures containing more than one volatile component: Partial pressure of each volatile component contributes to total vapor. Where x i = mole fraction of component i, and p i . = equilibrium vapor pressure of pure volatile component at a given temperature. A solution contains 100. 0 g of water (m = 18. 02 g/mol) and 25. 00 g of ethanol (m. P water = 23. 8 torr; p ethanol = 58. 7 torr. N total = 5. 549 mol + 0. 5427 mol = 6. 092 mol total. P total = (0. 9109 x 23. 8 torr) + (0. 08908 x 58. 7 torr) = 26. 9 torr. Colligative properties: solution properties that depend on concentration of solute particles, not the identity of particles. Changes in boiling point/freezing point of solutions depends on molality : Preferred concentration unit for properties involving temperature. For typical solutions: molality > molarity changes because it is independent of temperature. Boiling point elevation and freezing point depression.
