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Schedule to Exam 3

Date Day Topics
10/17FriDiscussed the Exam 2 results which were quite high. Note a lot to discuss when most questions were answered quite well. Presented the important gas laws by name: Boyle's Law, Charles' Law, and Avogadro's Law. All put together as one in the "combined gas law". In that form the constant that PV/nT equals is a fundamental constant known as R, the universal gas constant. A rearrangement gave the familiar Ideal Gas Law: PV = nRT
10/20MonDiscussed the details of pressure. Defined as force/area. Talked about the way in which a barometer works. How to calculate the pressure that supports a column of liquid: P = ρ g h where ρ is the density of the liquid in kg/mL, g is the acceleration constant for gravity (9.81 m/s2), and h is the column height in meters. The pressure units will be pascals, Pa. Also described Dalton's Law of Partial Pressures. Also covered the concentration term mole fraction.
10/22WedKinetic Molecular Theory for Gases. Looked at how kinetic energy is directly proportional to the Kelvin temperature for a gas. Effusion and diffusion were defined and the average velocity of gas particles (actually the rms velocity) were compared to the molar mass (M) and the temperature (T).
10/24FriChapter 5 - Real Gases. Talked about the key differences in real gases and ideal gases. This is section 5.10 in your book. Also defined the compression factor (Z) which is the observed molar volume divided by the "ideal" molor volume. Z is mathmatically equivalent to the ratio PV/nRT where the V in that equation is the actual observed volume of a real gas sample. We looked at the plots of Z vs P and identified the regions: less than 1 was where attractive forces are dominant, and greater than 1 is where repulsive forces govern. Then I showed the "tweaked" version of the ideal gas law known as the van der Waal's Equation. We discussed the meaning of the two variables a and b in that equation.
10/27MonFinished up Chapter 5. Discussed standard molar volume at STP which happens to be 22.4 L. Also the fact that a balanced chemical equation can be view as "volumes" of gas and not just moles of gas. Started Chapter 16 on condensed phases - solids and liquids. What holds a typical molecular solid together? a liquid? Intermolecular forces. There are 3 of these that you must know: dipole-dipole interaction which is present for all polar substances. A special case of dipole-dipole when H is covalently bound to N, O, or F results in H-bonding. The last IMF is London (dispersion) forces which are present in ALL compounds, both polar and non-polar. London forces are the ONLY force present for non-polar compounds. They are set up via momentary charge shifts that lead to temporary dipoles. Once set up these temporary dipoles can induce more dipoles and the attractions are in place.
10/28Tue H10 is due by 11:59 AM (this is by noon)
10/29WedLooked more at intermolecular forces. Each force has an associated potential energy equation that we looked at. These equations are on the review sheet for Chapter 16 that is available on our website. Knowing the trends in IMF we then looked at some physical properties: boiling point, surface tension, capillary action, formation of a meniscus. IMF's are the forces behind cohesive and adhesive forces. We looked at the differences and then how water "wants" to wet clean glass and will bead up on waxed surfaces. Hydrophilic and hydrophobic interactions. Showed the scientific definition of boiling point and normal boiling point.
10/31FriHALLOWEEN! --- More chapter 16 and in particular - vapor pressure. Stopped early to have a lovely demonstration of hot vs cold which was hot water into cold liquid nitrogen. LOTS of cloudiness... if you shoot pictures/video... send me a copy or send me a link.
11/3MonMore on intermolecular forces and vapor pressure.
11/4Tue H11 is due by 11:59 AM (this is by noon)
11/5WedShort discussion about exam 3. 25 questions - about 15 from Chapter 5 and 10 from chapter 16. Introduced Thermodynamics. Discussed some of the drudgery of learning thermodynamics. Defined the 3 types of systems: open, closed, and isolated. Defined the First Law of Thermodynamics.
11/6ThuEXAM 3, 7-9 PM