Solutions II - COLLIGATIVE PROPERTIES Colligative...

Info icon This preview shows pages 1–14. Sign up to view the full content.

View Full Document Right Arrow Icon
COLLIGATIVE PROPERTIES
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Colligative Properties of Solutions Colligative properties are properties of solutions that depend solely on the number of particles dissolved in the solution. Colligative properties do not depend on the kinds of particles dissolved. Colligative properties are a physical property of solutions.
Image of page 2
Colligative Properties of Solutions There are four common types of colligative properties: 1. Vapor pressure lowering 2. Freezing point depression 3. Boiling point elevation 4. Osmotic pressure Vapor pressure lowering is the key to all four of the colligative properties.
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Lowering of Vapor Pressure and Raoult’s Law Addition of a nonvolatile solute to a solution lowers the vapor pressure of the solution. The effect is simply due to fewer solvent molecules at the solution’s surface. The solute molecules occupy some of the spaces that would normally be occupied by solvent. Raoult’s Law models this effect in ideal solutions.
Image of page 4
Lowering of Vapor Pressure and Raoult’s Law
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Lowering of Vapor Pressure and Raoult’s Law Derivation of Raoult’s Law. P P where P vapor pressure of solvent P vapor pressure of pure solvent mole fraction of solvent solvent solvent solvent 0 solvent solvent 0 solvent X in solution X in solution
Image of page 6
Lowering of vapor pressure, P solvent , is defined as: 0 solvent solvent 0 solvent solvent 0 solvent solvent 0 solvent solvent )P 1 ( ) P )( ( - P P P P X X Lowering of Vapor Pressure and Raoult’s Law
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Remember that the sum of the mole fractions must equal 1. Thus X solvent + X solute = 1, which we can substitute into our expression. Law s Raoult' is which P P - 1 0 solvent solute solvent solvent solute X X X Lowering of Vapor Pressure and Raoult’s Law
Image of page 8
Fractional Distillation Distillation is a technique used to separate solutions that have two or more volatile components with differing boiling points. A simple distillation has a single distilling column. Simple distillations give reasonable separations. A fractional distillation gives increased separations because of the increased surface area. Commonly, glass beads or steel wool are inserted into the distilling column.
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Fractional Distillation
Image of page 10
Boiling Point Elevation Addition of a nonvolatile solute to a solution raises the boiling point of the solution above that of the pure solvent. This effect is because the solution’s vapor pressure is lowered as described by Raoult’s law. The solution’s temperature must be raised to make the solution’s vapor pressure equal to the atmospheric pressure. The amount that the temperature is elevated is determined by the number of moles of solute dissolved in the solution.
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Boiling Point Elevation Boiling point elevation relationship is: solvent for the constant elevation point boiling molal K solute of ion concentrat molal elevation point boiling T : where K T b b b b m m
Image of page 12
Boiling Point Elevation
Image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 14
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern