1. Lecture 1910/17/05 Seminar today Review Session?

2. Assumption: Gas molecules occupy no space Volume actually occupied by O 2 molecules: Volume ~ 4.63 x 10 -27 L/molecule Volume ~ 2.79 x 10 -3 L/mol Total volume occupied by O 2 molecules at STP (use PV=nRT): 22.4 L/mol

3. Assumption: Gas molecules occupy no space Volume actually occupied by O 2 molecules: Volume ~ 2.79 x 10 -3 L/mol Total volume occupied by O 2 molecules at 273 K and 100 atm: 0.224 L/mol Total volume occupied by O 2 molecules at 273 K and 1000 atm: 0.0224 L/mol

4. Assumption: Gas molecules don’t interact with each other All gases can be liquefied, so can have interaction Interactions will decrease force of collision on wall So will decrease pressure

5. Correction for Pressure n = moles V = volume a = constant [typically between 0.01 to 10 atm(L/mol) 2 ] What happens to P when n or V changes?

6. Correction for Volume n = moles V = volume b = constant [typically between 0.01 to 0.1 L/mol] What happens to V when n changes?

7. Van der Waals Equations 1.At moderately high pressures, intermolecular attractions dominate 2.At very high pressures, molecular volume dominates

8. Compare the ideal and the observed pressure for 10.0 mol of helium gas in a 1.00-L container at 25˚C. a = 0.034 atm-L 2 /mol 2 b = 0.0237 l/mol

9. The gas B 2 H 6 burns in air to give H 2 O and B 2 O 3 (s) 1) Place the 3 gases involved with this reaction in order of increasing molecular speed. 2) A 3.26-L flask contains B 2 H 6 with a pressure of 256 mm Hg at 25˚C. Suppose O 2 gas is added to the flask until B 2 H 6 and O 2 are in the correct stoichiometric ratio for the reaction. What is the partial pressure of O 2 ?

10. END OF MATERIAL FOR EXAM 2