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Colligative Properties, Colloids, Surfactants
Colligative properties of solutions properties depending on number of particles (ions, molecules) dissolved
Raoults Law of vapor pressure lowering: vp = vpo(mol. frac. solvent)
Elevation of b.p. and depression of f.p. similar: DT = K(molality)
Use these to determine molar masses of solutes
V der Ws alpha: anomalous results due to ionic dissociation
Osmosis: flow of solvent across semipermeable membranes; example red blood cells
Osmotic Pressure, PV =nRT where R is usual gas constant
Use osmotic pressure to determine molar masses of large molecules like proteins
Colloids: particles larger than ions/molecules but not large enough to settle
Tyndall effect: colloids scatter light
Soaps and surfactants: hydrophilic head and hydrophobic tail
Colligative Properties, Colloids, Surfactants
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
- Intro
- Colligative Properties and Raoult's Law
- Boiling Point Elevation, Freezing Point Depression
- Pure Water and Solution in Water
- Lower Vapor Pressure
- Higher Boiling Point (Elevation)
- Lower Freezing Point (Depression)
- Example: Antifreeze
- Change in Boiling Point (Molality)
- Molar Mass from Elevation and Depression
- Van der Waals' Alpha Factor
- Osmosis
- Osmotic Pressure
- Molar Mass from Osmotic Pressure
- Colloids and the Tyndall Effect
- Surfactants
- Soaps and Detergents
- Additional Example 1
- Additional Example 2
- Intro 0:00
- Colligative Properties and Raoult's Law 0:43
- Colligative (Collective)
- Raoult's Law
- Uses of Raoult's Law (Mole Fraction and Molar Mass)
- Boiling Point Elevation, Freezing Point Depression 5:47
- Pure Water and Solution in Water
- Lower Vapor Pressure
- Higher Boiling Point (Elevation)
- Lower Freezing Point (Depression)
- Example: Antifreeze
- Change in Boiling Point (Molality)
- Molar Mass from Elevation and Depression 12:49
- Example: Water and Cystine
- Van der Waals' Alpha Factor 18:59
- Alpha Factor Equation
- Example: Salt Ions
- Osmosis 23:02
- Blood (Isotonic, Hypertonic, Hypotonic)
- Osmotic Pressure 27:40
- Osmotic Pressure Definition (Pi)
- Van der Waals'
- Molar Mass from Osmotic Pressure 33:29
- Example: Peptide in Water
- Colloids and the Tyndall Effect 38:33
- Light Beam (Solution and Colloidal Suspension)
- Surfactants 44:11
- Example: Sodium Stearate (Soap)
- Soaps and Detergents 49:24
- Ordinary Soaps Problem
- Synthetic Soaps
- Additional Example 1
- Additional Example 2
0 answers
Post by Richard Meador on August 17, 2013
In calculating the molar mass on the "molar mass from depression and elevation" slide, the numerator of the equation has 2.9x10^3 g/M multiplied by 10^3 g/kg. The 10^3 g/kg is incorrect and should be deleted. The answer of 2.5 x 10^2 g/mol is correct.
0 answers
Post by Marian Iskandar on April 29, 2013
My values are completely different from what the professor has. I have 3.9x10^-2, not -4 for my m (molality), which essentially throws off the rest of the calculation. Does anyone else get the same answer? Just wanting to double check, thanks!
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Post by John Leffingwell on February 12, 2012
What is the difference between "van der Waals alpha factor" and the "van't Hoff factor"? When I Google "van der Waals alpha factor", I can't find anything, but when I Google "van't Hoff factor", I find TONS of pages describing the "alpha factor" you presented in this video.