Chem 402 Lecture 8: L8 2:3:17

4 Pages
Unlock Document

Washington University in St. Louis
University College - Chemistry
University College - Chemistry Chem 402
Barnes Alexander

3 February 2017 L8: 0 Law of Thermodynamics I. 4 Laws of Thermodynamics and Temperature A. Basics 1. Specific Heats (from L7) βˆ’Ξ˜ Ξ˜π‘£π‘–π‘ 𝑒 𝑇𝑣𝑖𝑏 a. 𝐢 𝑣,𝑣𝑖𝑏= π‘π‘˜( ) [ βˆ’Ξ˜π‘£π‘–π‘ ] 𝑇 (1βˆ’π‘’ 𝑇 )2 b. C v, rotR c. C v, trans3/2 R βˆ’Ξ˜π‘‡π‘–π‘ d. C v 𝑅 + 𝑅 + π‘π‘˜( Θ 𝑣𝑖) [ 𝑒 2] 2 𝑇 βˆ’Ξ˜π‘£π‘–π‘ (1βˆ’π‘’ 𝑇 ) β€’ However, for vibrational modes at 298K, all in the ground state, so we generally don’t regard the Cv, vibrm e. Therefore C =v(5/2)R 2. Definitions a. System β€’ Part of the universe that we chose to study b. Surroundings β€’ Rest of the universe c. Boundary β€’ The surface dividing the system from the surroundings (a barrier) 3. Systems a. Open β€’ Mass and energy can transfer between the system and the surroundings b. Closed β€’ Energy can transfer between the system and the surroundings, but not mass c. Isolated β€’ Neither mass nor energy can transfer between the system and the surroundings 4. 3 + 0 Laws # Variable Qualitative Microscopic Tease 0 T Defines temperature 1 U Energy cannot be created or All heat can be π‘ˆ = βˆ‘π‘ 𝐸 𝑖 𝑖 destroyed in the universe 𝑖 converted to work 𝑁 2 S Entropy increases in the universe π‘ž 100% heat to work as a whole with time 𝑆 = π‘˜π‘™π‘›( 𝑁! ) conversion can only occur at 0K 3 S Puts a # to entropy S = 1 at 0K You can’t get to 0K 5. Requirements to Describe a System a. A few macroscopic properties are required (p, T, V, n, m…) β€’ Extensive properties: depend on the size of the system (n, m, V, …) 𝑉 β€’ Intensive properties: independent of the size of the system (T, p, 𝑉𝑛= .._.) b. Knowledge if system is homogenous or heterogeneous β€’ Depends on scale, on a macro level we consider most things homogenous β€’ Ie- coffee may have milk, sugar, etc in it, but zoomed out it is just a homogenous β€œcoffee” c. Knowledge if system is in Eq’b state β€’ Eq’b thermodynamics is key, must define eq’b to describe a state d. Knowledge of the number of components B. Equilibria in Thermodynamics 1. The State of a System at Eq’b a. Defined by the collection of all macroscopic properties that are described by state variables (p, n, T, V, …)
More Less

Related notes for University College - Chemistry Chem 402

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.