Announcements To join clicker to class today: – Turn on the Clicker (the red LED comes on). – Push “Join” button followed by “20” followed by the “Send” button (switches to flashing green LED if successful). ● Exam 4 on Chapters 7 & 8 next Wednesday. ● All study material for these chapters is posted on web site. ● Do not forget about the Lewis Tutorial, the VSEPR examples on Web site and the text site as well for more examples and pictures. ● Quiz Monday on

Review PV = nRT –Solved for P = nRT/V –Solved for V = nRT/P –Solved for n = PV/(RT) –Solved of T = PV/(nR) Partial pressures –P tot = P 1 + P 2 + … = (n 1 + n 2 + …)RT/V –P i = X i P tot –∑  X i = 1 or X 1 + X 2 + X = 1 –Example of finding volume that would be occupied by one of the gases in a mixture.

Dalton’s Law to find volume contributed by a gas. PV = nRT & P tot = (n 1 +n 2 +..)RT P H2O = 0.20 atm, if P tot = 1.00 atm => P N2 = 1.00 – 0.20 = 0.80 atm. Given total V = L calculated n N2 =P N2 V tot /RT=1.3 x mol N 2. If there had been no water vapor than P N2 = 1.00 atm. Used this to calculate V N2 = n N2 RT/P tot = 36. mL.) Can be shorter if do it symbolicly first. Final equation: V N2 = P N2 V tot /P tot = (0.80 atm)(45 mL)/(1.00 atm)= 36. mL!

Henry’s Law of Gas Solubility C gas = k H P gas –C gas = molarity of gas in solution – k H = the Henry’s law constant for a particular gas in a particular solvent – P gas = the partial pressure of the gas –This law is an empirical observation.

Kinetic Molecular Theory of Gases Molecules assumed to be very small (essentially points with no volume) They are constantly moving and exchanging kinetic energy through elastic collisions => they are changing direction and speed randomly, but total kinetic energy constant. Pressure = sum of the force of many collisions with the walls of the container. Based on KE = (1/2)mu 2 (u = speed). Key result: u rms = (3RT/ M ) 1/2