M1 Entropy &amp; Gibbs Free Energy Problems

# M1 Entropy &amp; Gibbs Free Energy Problems - Solomons...

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S olomon’s Study Notes General Chemistry CHE 132 Spring 2009 Midterm 1 Solomon Weiskop PhD Chapter 18 Practice Problems (Entropy & Gibbs Free Energy)

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Study Notes & Practice Problems are available to print out by registering at www.solomonlinetutor.com Solomon Weiskop PhD Solomon’s CHE 1 32 Tutoring © Copyright 2009
1 Problems numbered in blue were written by Prof. Hanson [#1] Which statement about entropy is not correct? [Sp08Mid1#14] Note: q = energy transferred T = Kelvin temperature (a) Rudolf Clausius discovered the significance of the ratio q/T in his studies of heat engines, and called this quantity entropy. (b) Ludwig Boltzmann had the idea that entropy is a measure of the number of states over which energy is dispersed (c) The entropy of the system is zero when the system can only be in one state (d) In any spontaneous process, the entropy of the universe increases (e) In an endothermic process, the entropy of the system decreases [#2] If two quanta (units) of energy are distributed over 100 atoms, what is the probability of finding the energy dispersed, i.e. each quantum on a different atom. [Sp08Mid1#15] (a) 0.99 (b) 0.98 (c) 0.97 (d) 0.96 (e) 0.95 [#3] Which one of the following relationships is not correct? [Sp08Mid1#18] (a) ΔG < 0 for any spontaneous process (b) ΔS universe > 0 for any spontaneous process (c) ΔE = q + w (d) ΔG = ΔH –TΔS (e) At equilibrium ΔG 0 = 0 [#4] Which statement is not correct? [Sp07Mid2#10] A spontaneous reaction always _______ (a) disperses energy over more states (b) produces a decrease in free energy (c) leads to an increase in the entropy of the universe (d) occurs immediately (e) produces a more probable situation

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2 [#5] For the following constant-temperature process which one is not correct? (a) q sys < 0 (b) ΔS sys < 0 (c) ΔS sys > 0 (d) ΔS tot > 0 (e) q surr > 0 [#6] Which one is not correct? In any spontaneous process (a) ΔS univ > 0 (b) ΔS sys + ΔS surr > 0 (c) ΔS univ < 0 (d) ΔG sys < 0 (e) ΔS tot > 0 [#7] 6 moles of liquid water at 0°C freezes in a freezer set at 25°C. ΔH fus (water) = 6.01 kJ/mol What is the total entropy change (ΔS univ )? [#8] An ice cube with a mass of 9.00g falls into a swimming pool and melts. The temperature of the ice cube was 0°C and the temperature of the swimming pool was 20°C. Determine the change in entropy of the swimming pool caused by the ice cube melting. [Sp07Mid2#11] Given: for water ΔH fusion = 6.00kJ/mol MM = 18g/mol (a) +20.5 J/K (b) 10.2 J/K (c) +11.0 J/K (d) 20.5 J/K (e) +10.2 J/K [#9] Using the data below determine the standard entropy change for the following reaction [Sp08Mid1#20] N 2 g ± + 3H 2 g ± → 2NH 3 g ± Substance S 0 in J/molK N 2 (g) 191.6 H 2 (g) 130.7 NH 3 (g) 192.8 (a) 0 because entropy is conserved in a chemical reaction (b) +129.5 J/K (c) +198.1 J/K (d) 129.5 J/K (e) 198.1 J/K
3 [#10] An ice cube tray containing 155g ice at 0°C is put on a kitchen counter at 25°C. Find ΔS surr (in J/K) for the formation of 155g liquid water at 0°C. Given ΔH

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## This note was uploaded on 11/14/2010 for the course CHE 131 taught by Professor Kerber during the Spring '08 term at SUNY Stony Brook.

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M1 Entropy &amp; Gibbs Free Energy Problems - Solomons...

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