CHM1046 LECTURE NOTES12.7Colligative Properties: (dependent upon quantity) include boiling point elevation, Freezing point depression, and Osmotic pressure1. Boiling pt. elevation: ΔTb (change in boiling pt) ΔTb = m * kb- Higher molality (more solute you have), the larger ΔTb will beΔTb = Tb(solution) – Tb(pure solvent)- Larger ΔTb means boiling pt of solution is greater than boiling pt of pure solvent(example: salt water has a higher Tb than just water)- The more solute present, the higher the boiling pt of the solution2. Freezing pt. depression: ΔTfΔTf = Tf (solution) – Tf (solvent)ΔTf = m * kf- Higher molality means larger ΔTf- The freezing pt. of solution is lower than that of pure solvent3. Osmotic pressure:- Osmosis = the movement of solvent molecules from a less concentrated medium to a more concentrated medium through a semipermeable membrane- Osmotic pressure: (π): pressure required to stop the flow ofthe solvent molecules- Π = M * R * T(M = molarity, R= gas constant, which is 0.08206 L*atm/mol*K, and T = temperature(K)) In ionic solutions, the # of ions should be considered, using Vant Hoff factor (i)i= moles of particles in solution/ moles of formula unites dissolved In ionic solutions: ΔTf = i*m*kfTΔb = i*m*kb=
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