Consider the decomposition of a metal oxide to its elements, where M represents a generic metal. Substance AG°(kJ/mol) 3 M2O3(s) 2M(s) + 22(g) M2O3(s) -8.50 M(s) 0 What is the standard change in Gibbs energy for the reaction, as written, in the P forward direction? O2(g) 0 AG+xn = What is the equilibrium constant of this reaction, as written, in the forward direction at 298 K? K = What is the equilibrium pressure of O2(g) over M(s) at 298 K? Po₂ kJ/mol atm

Calculate the standard Gibbs free-energy change when SO3 forms from SO2 and O2 at 298 K. Why is sulfur trioxide an important substance to study? (Hint: What happens when it combines with water?)

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?

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?

Use the data in Appendix J to calculate rG andKPat 25 C for the reaction 2HBr(g)+Cl2(g)2HCl(g)+Br2() Comment on the connection between the sign of rG and the magnitude ofKP.

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?

For the reaction C2H2(g)+4F2(g)2CF4(g)+H2(g) S is equal to 358 J/K. Use this value and data from Appendix 4 to calculate the value of S for CF4(g).

Indicate whether the following processes are spontaneous or nonspontaneous. (a) Liquid water freezing at a temperature below its freezing point (b) Liquid water freezing at a temperature above its freezing point (c) The combustion of gasoline (d) A ball thrown into the air (e) A raindrop falling to the ground (f) Iron rusting in a moist atmosphere

For each process, tell whether the entropy change of the system is positive or negative, (a) A glassblower heats glass (the system) to its softening temperature, (b) A teaspoon of sugar dissolves in a cup of coffee. (The system consists of both sugar and coffee.) (c) Calcium carbonate precipitates out of water in a cave to form stalactites and stalagmites. (Consider only the calcium carbonate to be the system.)

What happens to the entropy of the universe during a spontaneous process?