Chem14B Outline 2 Thermodynamics PDF

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Professor - Laurence Lavelle...

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CHEM 14B WINTER 2015

Instructor: Dr. Laurence Lavelle

Thermodynamics: The Second & Third Laws Read: Ch 8 Do Problems: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 69, 71, 75, 81, 83, 85, 87, 89, 91, 93, 99, 101, 103, 105 Ch 10.3, 10.11 - 10.13 (The rest of Ch 10 was covered in Chem 14A.) Do Problems: 15, 17, 19, 21, 23, 83, 85, 105, 107, 109, 124 After going through the readings & problems and attending the lectures & discussion groups, you should be able to: •

State and explain the Boltzmann equation for entropy.

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Know how to calculate the number of microstates (W) to calculate entropy (S = kB ln W).

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Calculate the work of expansion when the pressure is not constant, w = -nRT ln

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Apply the 1st and 2nd laws of thermodynamics to calculate the change in energy and entropy of a system.

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State and explain the second (∆S =

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Explain how temperature, volume, and state of matter affect the entropy of a substance.

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Predict which of two systems has the greater entropy, given their compositions and conditions.

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Calculate changes in entropy due to changes in volume (∆S = n R ln

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T2 Calculate changes in entropy due to changes in temperature (∆S = n C ln T1 ).

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Calculate the standard reaction entropy from standard molar entropies.

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Show how ∆S is related to ∆H for a change at constant temperature and pressure and explain the relationship.

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Show how the Gibbs free energy change accompanying a process is related to the direction of spontaneous reaction.

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Predict the temperature at which a process with a known ∆H and ∆S becomes spontaneous.

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Calculate a standard reaction free energy from the standard enthalpy of reaction and standard molar entropies (∆G°RXN = ∆H°RXN - T∆S°RXN).

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Calculate the standard reaction free energy from standard free energies of formation

V2 V1 .

qREV T ) and third law of thermodynamics (lim T---> 0K S = 0).

(∆G°RXN = Σ∆G°f(PRODUCTS) - Σ∆G°f(REACTANTS)).

V2 ). V1

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Understand why reaction free energy depends on pressure and the equilibrium constant.

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Calculate reaction free energy from ∆G° and the composition of the reaction mixture (K).

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Calculate an equilibrium constant from ∆G° using ∆G° = - RT ln K.

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∆H° ∆S° Know how to derive and use the van't Hoff equation (ln K = - RT + R ) to show the temperature dependence of K, and calculate K at different temperatures.

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Use a ‘Chemisty’ van't Hoff analysis to calculate ∆H°, ∆S° and ∆G°.

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Understand the relationship between free energy and work....