Principles & Modern Applications General Chemistry Principles & Modern Applications 9th Edition Petrucci/Harwood/Herring/Madura Chapter 19 Spontaneous Change: Entropy and Free Energy Dr. Travis D. Fridgen Memorial University of Newfoundland © 2007 Pearson Education

Which of the following processes would you expect to result in a greater positive change in entropy? None of these processes involve positive entropy changes.

Which of the following processes would you expect to result in a greater positive change in entropy? None of these processes involve positive entropy changes.

Which of the following statements is incorrect? The absolute entropy for gaseous C2H6 is lower than that for gaseous C3H8 at the same temperature. 2. The entropy of formation for gaseous C3H8 is negative. 3. The entropy of formation of gaseous C3H8 is more negative than the entropy of formation for C2H6. 4. The absolute entropy for gaseous C3H8 decreases when the temperature is increased. 5. DfusS (solid to liquid) for H2O is greater than that for C3H8.

Which of the following statements is incorrect? The absolute entropy for gaseous C2H6 is lower than that for gaseous C3H8 at the same temperature. 2. The entropy of formation for gaseous C3H8 is negative. 3. The entropy of formation of gaseous C3H8 is more negative than the entropy of formation for C2H6. 4. The absolute entropy for gaseous C3H8 decreases when the temperature is increased. 5. DfusS (solid to liquid) for H2O is greater than that for C3H8.

The entropy change for the decomposition of ozone forming diatomic oxygen, is positive because two moles of gas are forming three moles of gas. 2. is close to zero because there are the same number of atoms on each side of the equation. 3. is negative because energy is released as the reaction proceeds. 4. is close to zero because both ozone and oxygen are in the gas phase. 5. None of the above answers makes sense.

The entropy change for the decomposition of ozone forming diatomic oxygen, is positive because two moles of gas are forming three moles of gas. 2. is close to zero because there are the same number of atoms on each side of the equation. 3. is negative because energy is released as the reaction proceeds. 4. is close to zero because both ozone and oxygen are in the gas phase. 5. None of the above answers makes sense.

Which of the following reactions, occurring when propane is burned, would you expect to be the most entropically favored (most positive change in entropy)?

Which of the following reactions, occurring when propane is burned, would you expect to be the most entropically favored (most positive change in entropy)?

In which of the following processes involving CO2 do you think the standard free energy change not make sense?

In which of the following processes involving CO2 do you think the standard free energy change not make sense?

Which of the following compounds would obey Trouton’s rule most closely? 1. 2. 3.

Which of the following compounds would obey Trouton’s rule most closely? 1. 2. 3.

Edgar Fahs Smith Collection University of Pennsylvania Library At room temperature ~290 K the reaction of H2 and O2 to form water: 1. is spontaneous because it is exothermic. 2. is non-spontaneous because DS is negative. J. W. Gibbs 3. is spontaneous because DS is negative. Edgar Fahs Smith Collection University of Pennsylvania Library 4. is spontaneous because DG is negative. 5. is spontaneous because DG is positive.

Edgar Fahs Smith Collection University of Pennsylvania Library At room temperature ~290 K the reaction of H2 and O2 to form water: 1. is spontaneous because it is exothermic. 2. is non-spontaneous because DS is negative. J. W. Gibbs 3. is spontaneous because DS is negative. Edgar Fahs Smith Collection University of Pennsylvania Library 4. is spontaneous because DG is negative. 5. is spontaneous because DG is positive.

Which of the following processes would you expect to be spontaneous at all temperatures? 1. 2. 3. 4. None are spontaneous at all temperatures. 5. All are spontaneous irrespective of the temperature.

Which of the following processes would you expect to be spontaneous at all temperatures? 1. 2. 3. 4. None are spontaneous at all temperatures. 5. All are spontaneous irrespective of the temperature.

The transformation between ice and water: Is spontaneous in the directions written because DS is positive. 2. Is spontaneous in the backwards direction because DH is positive. 3. Is spontaneous in the forward direction above 273 K and spontaneous in the backward direction below 273 K. 4. All three answers are correct. 5. There is not enough information provided to answer this question.

The transformation between ice and water Is spontaneous in the directions written because DS is positive. 2. Is spontaneous in the backwards direction because DH is positive. 3. Is spontaneous in the forward direction above 273 K and spontaneous in the backward direction below 273 K. 4. All three answers are correct. 5. There is not enough information provided to answer this question.

A mixture of H2 and O2 can sit in a flask almost indefinitely at 298 K without reacting. ? What is the best explanation for the absence of observable reaction? 1. A significant energy barrier hinders the start of the reaction. 2. The reaction is not spontaneous at this temperature. 3. The reaction is entropically unfavorable. 4. All three of these factors contribute. 5. None of the above answers is correct.

A mixture of H2 and O2 can sit in a flask almost indefinitely at 298 K without reacting. ? What is the best explanation for the absence of observable reaction? 1. A significant energy barrier hinders the start of the reaction. 2. The reaction is not spontaneous at this temperature. 3. The reaction is entropically unfavorable. 4. All three of these factors contribute. 5. None of the above answers is correct.

There is enough energy in lightning bolts that O2 and N2 in the atmosphere are decomposed into N and O atoms. The reaction of N and O to form NO, 1. is spontaneous at all temperatures. 2. is non-spontaneous at all temperatures. is spontaneous at high temperatures but non-spontaneous at low temperatures. 4. is spontaneous at low temperatures but non-spontaneous at high temperatures. 5. It is impossible to choose between the above responses without thermochemical data.

There is enough energy in lightning bolts that O2 and N2 in the atmosphere are decomposed into N and O atoms. The reaction of N and O to form NO, 1. is spontaneous at all temperatures. 2. is non-spontaneous at all temperatures. is spontaneous at high temperatures but non-spontaneous at low temperatures. 4. is spontaneous at low temperatures but non-spontaneous at high temperatures. 5. It is impossible to choose between the above responses without thermochemical data.

Below is some thermochemical data for diamond and graphite. True or false, equilibrium favors graphite in the above reaction. 1. True 2. False 3. The proportion of diamond and graphite are equal. 4. Cannot determine from the data given.

Below is some thermochemical data for diamond and graphite. True or false, equilibrium favors graphite in the above reaction. 1. True 2. False 3. The proportion of diamond and graphite are equal. 4. Cannot determine from the data given.

1. The equilibrium constant is 1. When DG = 0, 1. The equilibrium constant is 1. 2. The system has reached equilibrium. System free energy, G 3. The reaction will be too slow to observe. 4. All of the above are correct. 5. 1 and 2 above are both correct. Reactants Products

1. The equilibrium constant is 1. When DG = 0, Q<K 1. The equilibrium constant is 1. DGo 2. The system has reached equilibrium. System free energy, G 3. The reaction will be too slow to observe. Q>K 4. All of the above are correct. Q=K equilibrium 5. 1 and 2 above are both correct. Reactants (std state) Products (std state) DG = G(P)-G(R) = 0

The equilibrium constant for the decomposition of colorless dinitrogen tetroxide to form brown nitrogen dioxide favors reactants at all temperatures. favors products at all temperatures. favors reactants high temperatures only 4. favors products at high temperatures only. 5. It is impossible to choose between the above responses without thermochemical data.

The equilibrium constant for the decomposition of colorless dinitrogen tetroxide to form brown nitrogen dioxide favors reactants at all temperatures. favors products at all temperatures. favors reactants high temperatures only 4. favors products at high temperatures only. 5. It is impossible to choose between the above responses without thermochemical data.

CO binds to iron in hemoglobin more favorably than does oxygen, which is why CO is poisonous. What is the free energy change for O2 replacing CO bound to iron of hemoglobin? 1. 150 kJ mol-1 4. -150 kJ mol-1 2. 10 kJ mol-1 5. 5600 kJ mol-1 3. -10 kJ mol-1

CO binds to iron in hemoglobin more favorably than does oxygen, which is why CO is poisonous. What is the free energy change for O2 replacing CO bound to iron of hemoglobin? 1. 150 kJ mol-1 4. -150 kJ mol-1 2. 10 kJ mol-1 5. 5600 kJ mol-1 3. -10 kJ mol-1

The White Cliffs of Dover, England are made of chalk, CaCO3, which obviously has a very low solubility, Ksp is ~1 x 10-13 at 298 K. DGo for the dissolution of CaCO3 is: From http://www.dover-web.co.uk/ 1. ~ 70 kJ mol-1 2. ~ 10 kJ mol-1 3. ~ 1 kJ mol-1 4. ~ -10 kJ mol-1 5. ~ -70 kJ mol-1

The White Cliffs of Dover, England are made of chalk, CaCO3, which obviously has a very low solubility, Ksp is ~1 x 10-13 at 298 K. DGo for the dissolution of CaCO3 is: From http://www.dover-web.co.uk/ 1. ~ 70 kJ mol-1 2. ~ 10 kJ mol-1 3. ~ 1 kJ mol-1 4. ~ -10 kJ mol-1 5. ~ -70 kJ mol-1