For the reaction Mg²+ + Cu (s) Mg (s) + Cu²“, K = 10ʻ9² and ASº = +18 J/(K-mol). 2. %3D Under standard conditions, is AG° positive or negative? The term "standard conditions" means that reactants and products are in their standard states. b. Under standard conditions, is the reaction endothermic or exothermic? a.

For the reaction Mg²+ + Cu (s) Mg (s) + Cu²“, K = 10ʻ9² and ASº = +18 J/(K-mol). 2. %3D Under standard conditions, is AG° positive or negative? The term "standard conditions" means that reactants and products are in their standard states. b. Under standard conditions, is the reaction endothermic or exothermic? a.

Chemistry by OpenStax (2015-05-04)

1st Edition

ISBN:9781938168390

Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser

Publisher:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark Blaser

Chapter16: Thermodynamics

Section: Chapter Questions

Problem 31E: A reaction has H298=100 kj/mol and S298=250 J/mol K. Is the reaction spontaneous at room...

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The free energy change, G, for a process at constant temperature and pressure is related to Suniv and reflects the spontaneity of the process. How is G related to Suniv? When is a process spontaneous? Nonspontaneous? At equilibrium? G is a composite term composed of H, T, and S. What is the G equation? Give the four possible sign combinations for H and S. What temperatures are required for each sign combination to yield a spontaneous process? If G is positive, what does it say about the reverse process? How does the G = H TS equation reduce when at the melting-point temperature of a solid-to-liquid phase change or at the boiling-point temperature of a liquid-to-gas phase change? What is the sign of G for the solid-to-liquid phase change at temperatures above the freezing point? What is the sign of G for the liquid-to-gas phase change at temperatures below the boiling point?
Some water is placed in a coffee-cup calorimeter. When 1.0 g of an ionic solid is added, the temperature of the solution increases from 21.5C to 24.2C as the solid dissolves. For the dissolving process, what are the signs for Ssys, Ssurr, and Suniv?
For the reaction NO(g)+NO2(g)N2O3(g) , use tabulated thermodynamic data to calculate H and S. Then use those values to answer the following questions. (a) Is this reaction spontaneous at 25°C? Explain your answer. (b) If the reaction is not spontaneous at 25°C, will it become spontaneous at higher temperatures or lower temperatures? (c) To show that your prediction is accurate, choose a temperature that corresponds to your prediction in part (b) and calculate G . (Assume that both enthalpy and entropy are independent of temperature.)
What is the third law of thermodynamics? What are standard entropy values, S, and how are these S values (listed in Appendix 4) used to calculate S for a reaction? How would you use Hesss law to calculate S for a reaction? What does the superscript indicate? Predicting the sign of S for a reaction is an important skill to master. For a gas-phase reaction, what do you concentrate on to predict the sign of S? For a phase change, what do you concentrate on to predict the sign of S? That is, how are Ssolid, Sliquid, and Sgas related to one another? When a solute dissolves in water, what is usually the sign of S for this process?
A reaction has H298=100 kj/mol and S298=250 J/mol K. Is the reaction spontaneous at room temperature? If not, under what temperature conditions will it become spontaneous?
Silver carbonate, Ag2CO3, is a light yellow compound that decomposes when heated to give silver oxide and carbon dioxide: Ag2CO3(s)Ag2O(s)+CO2(g) A researcher measured the partial pressure of carbon dioxide over a sample of silver carbonate at 220C and found that it was 1.37 atm. Calculate the partial pressure of carbon dioxide at 25C. The standard enthalpies of formation of silver carbonate and silver oxide at 25C are 505.9 kJ/mol and 31.05 kJ/mol, respectively. Make any reasonable assumptions in your calculations. State the assumptions that you make, and note why you think they are reasonable.
10.104 (a) When a chemical bond forms, what happens to the entropy of the system? (b) Thermodynamically, what allows any bond formation to occur? (c) What do your answers to parts (a) and (b) suggest must be true about the formation of chemical bonds for the octet rule to hold?
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For the reaction at 298 K, 2NO2(g)N2O4(g) the values of H and S are 58.03 kJ and 176.6 J/K, respectively. What is the value of G at 298 K? Assuming that H and S do not depend on temperature, at what temperature is G = 0? Is G negative above or below this temperature?
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