Chem%20162-2011%20lecture%204

Chem%20162-2011%20lecture%204 - CHEMISTRY 162-2011 LECTURE...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 162-2011 Lecture 3 1 CHEMISTRY 162-2011 LECTURE 4 ANNOUNCEMENTS E-MAIL ATTENDANCE Sign in QUIZ Recitation quiz this week MISCELLANEOUS
Background image of page 1

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

View Full DocumentRight Arrow Icon
Chem 162-2011 Lecture 3 2 PLAN FOR TODAY : BALANCE OF LECTURE 3 Electrolytes Colloids LECTURE 4 - CHEMICAL KINETICS (13.3 – 13.6) Reaction rates Rate laws from experimental data - Initial Rates Method Integrated rate laws - Half-lives
Background image of page 2
Chem 162-2011 Lecture 3 3 COLLIGATIVE PROPERTIES VAPOR PRESSURE Most solution properties depend on the identity of the solute; e.g., solubility: KNO 3 is more soluble in H 2 O than AlPO 4 . Colligative properties don’t depend on the identity of the solute, only on the concentration (of particles) of the solute; e.g., 0.1m glucose and 0.1m urea (and 0.05m NaCl*) have the same number of particles, and therefore the same vapor pressure, boiling point, freezing point and osmotic pressure. *Note that 1 mole of glucose provides 1 mole of particles; 1 mole of urea provides 1 mole of particles; 1 mole of NaCl provides 2 moles of particles (0.5 mole NaCl provides 1 mole of particles). ET: Discuss vapor pressure Determine the vapor pressure of a 22 o C solution made up of 1 mol H 2 O and 2 mol glucose (C 6 H 12 O 6 ). Glucose does not dissociate and is not volatile. P o H2O @ 22 o C = 21 mm. Raoult’s Law: P soln /X solvent = P o solvent which means that the concentration of the substance in the gas phase to the concentration of the substance in the liquid phase is a constant, which means that if you decrease the concentration of the volatile substance in the liquid phase then the concentration must decrease in the gas phase. This is identical to Henry’s law, except for the state focus. P soln = X solvent P o solvent P soln = (n H2O /(n H2O + n C6H12O6 )) x P o H2O P soln = (1/(2+1)) x 21 = 7 mm P soln = P X solvent P o solvent P soln = (in H2O /(in H2O + in NaCl )) x P o H2O P soln = ((1x1)/((1x1) + (2x1))) x 21 = 7 mm H 2 O C 6 H 12 O 6 C 6 H 12 O 6 H 2 O H 2 O H 2 O Na + Cl - H 2 O 2 molecules glucose = 2 particles 1 molecule NaCl = 2 particles
Background image of page 3

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

View Full DocumentRight Arrow Icon
Chem 162-2011 Lecture 3 4 SOLUTIONS OF ELECTROLYTES VAN’T HOFF FACTOR (“i”) The van’t Hoff factor (i) is a correction factor that must be incorporated into equations for colligative properties so that the equations may be applied to solutions of strong or weak electrolytes. 69 (mod) What is the van’t Hoff factor for the following: Na 3 PO 4 , CaBr 2 , KCl, CH 3 OH Al 2 (SO 4 ) 3 2Al 3+ + 3SO 4 2- i = 5 Na 3 PO 4 3 Na + + PO 4 3- i = 4 CaBr 2 Ca 2+ + 2Br - i = 3 KCl K + + Cl - i = 2 CH 3 OH* i = 1 * Assume that all salts dissociate completely, although the degree of dissociation depends on the concentration of the salt. Organic molecules, in general, other than organic acids do not dissociate. Organic acids dissociate slightly.
Background image of page 4
Chem 162-2011 Lecture 3 5 Variation of the van’t Hoff Factor, i, with Solution Molality Molality, m Solute 1.0 0.10 0.010 0.0010 . . . Infinite dilution NaCl 1.81 1.87 1.94 1.97 . . . 2 MgSO 4 1.09 1.21 1.53 1.82 . . . 2 Pb(NO 3 ) 2 1.31 2.13 2.63 2.89 . . . 3 In concentrated solutions of strong electrolytes, attractive forces between cations and anions cause some of them to associate into ion pairs .
Background image of page 5

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

View Full DocumentRight Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/08/2011 for the course CHEM 162 taught by Professor Siegal during the Spring '08 term at Rutgers.

Page1 / 26

Chem%20162-2011%20lecture%204 - CHEMISTRY 162-2011 LECTURE...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online