Lecture 2-equilibrium

Lecture 2-equilibrium - Chemistry 271, Fall 2009 General...

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Chemistry 271, Fall 2009 General Chemistry and Energetics Lecture #2: Ideal Gas Law, Dynamic Equilibrium, Le Chatelier’s Principle, and the Equilibrium Constant Jason D. Kahn Dept. of Chemistry and Biochemistry jdkahn@umd.edu

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9/2/09 Lecture 2, Chemistry 271, Fall 2009, Jason Kahn Slide 2 Course Mechanics Discussion sections start next week (9/8/09). Advice on how to succeed (or fail) is available on Elms under Course Documents. We will start the SmartWork assignments soon. If you did not get an email from the class reflector (chem271-22all-fall09@coursemail.umd.edu), please let me know. No class Monday (Labor Day).
Lightning review of the Ideal Gas Law P = pressure (force per unit area; atmospheres) -- this is a property of many-molecule systems, the force comes from many collisions with the walls. How does P depend on other variables? What are the other variables? 9/2/09 Lecture 2, Chemistry 271, Fall 2009, Jason Kahn Slide 3

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Lightning review of the Ideal Gas Law P = pressure (force per unit area; atmospheres) -- this is a property of many-molecule systems, the force comes from many collisions with the walls. V = volume (liters) n = # of moles = # of particles/N A , N A = Avogadro’s number = 6.02 x 10 23 particles/mole R = Universal gas constant = 8.3145 Joule/(mole K) = 0.08206 liter•atmosphere/(mole K) = 1.987 cal/(mole K) T = absolute (Kelvin) T. 0 K = –273.15 C Boyle’s Law: PV is constant at constant n,T Charles’ Law: P/T is constant at constant n, V Avogadro’s Law: P/n is constant at constant V, T 9/2/09 Slide 4 Lecture 2, Chemistry 271, Fall 2009, Jason Kahn
Ideal Gas Law (Chapter 6) PV = nRT (Calculations: knowing any three of P, V, n, T you calculate the 4 th , ad nauseum. ) An ideal gas is one in which all of the particles have zero excluded volume and they all ignore each other (that’s why R is universal…). At T = 0, P = 0 -- there is no molecular motion. That is absolute zero, zero on the Kelvin scale, which is why we always use the Kelvin scale. T is a measure of the average kinetic energy per particle. This is actually how T is defined. Real gases approach ideal behavior at low P, high T. The ideal gas is a useful yardstick system for real systems. We will assume the ideal gas law, and we assume independent partial pressures of gases in a mixture. (Dalton’s Law – the gases ignore each other, but they all press on the surface of the vessel. 9/2/09 Slide 5 Lecture 2, Chemistry 271, Fall 2009, Jason Kahn

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9/2/09 Lecture 2, Chemistry 271, Fall 2009, Jason Kahn Slide 6 Let’s jump in… Reading: Skim Chapter 6:1-6 Read Chapter 15, sections 1, 2, 3, 4, 6, 7, 8 Problems: Ch. 15: 4, 10, 13, 20, 21, 57, 77, 81, 96, 104, 126 = practice with the numerical manipulations that I may not cover in class. Some will be included in a SmartWork assignment – this gives you a head start. Note that there are a lot of calculations that you need to
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This note was uploaded on 01/24/2011 for the course CHEM 271 taught by Professor Staff during the Spring '08 term at Maryland.

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Lecture 2-equilibrium - Chemistry 271, Fall 2009 General...

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