Problems

Author: John Hutchinson

Problem 1	Each possible sequence of the 52 cards in a deck is equally probable. However, when you shuffle a deck and then examine the sequence, the deck is never ordered. Explain why in terms of microstates, macrostates, and entropy.
Problem 2	Assess the validity of the statement, "In all spontaneous processes, the system moves toward a state of lowest energy." Correct any errors you identify.
Problem 3	In each case, determine whether spontaneity is expected at low temperature, high temperature, any temperature, or no temperature: ΔH°>0, ΔS°>0 ΔH°<0, ΔS°>0 ΔH°>0, ΔS°<0 ΔH°<0, ΔS°<0
Problem 4	Using thermodynamic equilibrium arguments, explain why a substance with weaker intermolecular forces has a greater vapor pressure than one with stronger intermolecular forces.
Problem 5	Why does the entropy of a gas increase as the volume of the gas increases? Why does the entropy decrease as the pressure increases?
Problem 6	For each of the following reactions, calculate the values of ΔS°, ΔH°, and ΔG° at T=298K and use these to predict whether equilibrium will favor products or reactants at T=298K. Also calculate Kp. 2CO(g)+O2(g) 2CO2(g) O3(g)+NO(g) NO2(g)+O2(g) 2O3(g) 3 O2(g)
Problem 7	Predict the sign of the entropy for the reaction 2H2(g)+O2(g) 2H2O(g) Give an explanation, based on entropy and the Second Law, of why this reaction occurs spontaneously.
Problem 8	For the reaction H2(g) 2H(g), predict the sign of both ΔH° and ΔS°. Should this reaction be spontaneous at high temperature or at low temperature? Explain.
Problem 9	For each of the reactions in exercise 6, predict whether increases in temperature will shift the reaction equilibrium more towards products or more towards reactants.
Problem 10	Using equation 7 and equation 9, show that for a given set of initial partial pressures where Q is larger than Kp, the reaction will spontaneously create more reactants. Also show that if Q is smaller than Kp, the reaction will spontaneously create more products.