1 / 4

-- these depend on the concentration of particles in a solution, but not...

Francois Marie Raoult (1830 – 1901). Colligative Properties. -- these depend on the concentration of particles in a solution, but not. the kind of particles. (A) Adding a volatile /nonvolatile solute to a solvent increases / decreases the solution’s vapor pressure (VP).

shada
Télécharger la présentation

-- these depend on the concentration of particles in a solution, but not...

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Francois Marie Raoult (1830 – 1901) Colligative Properties -- these depend on the concentration of particles in a solution, but not... the kind of particles (A) Adding a volatile/nonvolatile solute to a solvent increases/ decreases the solution’s vapor pressure (VP). Use this eq. once for every substance in mix. that has a measureable VP. Raoult’s law: PA, mix = XA PoA PA, mix = VP of particle type “A” above the mixture XA = mole fraction of particle type “A” in the mixture PoA = VP of “pure A”

  2. Ideal solutions obey Raoult’s law. Such solutions have... -- a low concentration (i.e., are relatively dilute) -- solute and solvent particles that are similar in size and have similar IMFs

  3. A solution of sodium chloride and water has a vapor pressure of 0.854 atm at 100.oC. Find the mole fraction of sodium chloride. (Key #1: NaCl is nonvolatile, so VP above the mixture is due entirely to H2O.)  PH2O, mix = XH2O PoH2O PA, mix = XA PoA (Key #2: The VP of H2O @ 100.oC should be recognizable.)  XH2O = 0.854 0.854 atm = XH2O (1.00 atm) and so X is 0.146 for all other particles If the solute were sucrose, Xsucrose = 0.146. But here… XNaCl = 0.073 because then… XNa+ + XCl– = 0.146

  4. CH3CH2OH Xeth = 0.127 XH2O = 0.873 A solution contains 89.7 g ethanol and 241.4 g water. What is the vapor pressure above the mixture at 100.oC, if ethanol’s vapor pressure at this temp. is 1694 torr? (Find VP of each substance, then use Dalton’s law to find Ptot.) 89.7 g eth = 1.95 mol eth 241.4 g H2O = 13.41 mol H2O Ptot, mix = PH2O, mix + Peth, mix Peth, mix = Xeth Poeth = 0.127(1694) = 215 torr Ptot = 879 torr PH2O, mix = XH2O PoH2O = 0.873(760) = 664 torr

More Related