Use the observations about each chemical reaction in the table below to decide the sign (positive or negative) of the reaction enthalpy AH and reaction entropyAS.Note: if you have not been given enough information to decide a sign, select the "unknown" option.reactionobservationsconclusionsAH is (pick one)The reverse of this reaction is alwaysspontaneous but proceeds faster atAtemperatures above 25. °C.AS is(pick one) vThis reaction is spontaneous except belowAH is(pick one)63. °C but proceeds at a faster rate above117. °C.AS is(pick one) vAH iSThis reaction is always spontaneous, butproceeds faster at temperatures above(pick one) vC115. °C.AS is(pick one)

Use the observations about each chemical reaction in the table below to decide the sign (positive or negative) of the reaction enthalpy AH and reaction entrop AS. Note: if you have not been given enough information to decide a sign, select the "unknown" option. reaction observations conclusions AH is (pick one) v The reverse of this reaction is always spontaneous but proceeds faster at temperatures above 25. °C. A. AS is (pick one) v This reaction is spontaneous except below 63. °C but proceeds at a faster rate above AH is (pick one) v 117. °C. AS is (pick one) v AH is (pick one) v This reaction is always spontaneous, but proceeds faster at temperatures above 115. °C. AS is (pick one) v

Use the observations about each chemical reaction in the table below to decide the sign (positive or negative) of the reaction enthalpy AH and reaction entrop AS. Note: if you have not been given enough information to decide a sign, select the "unknown" option. reaction observations conclusions AH is (pick one) v The reverse of this reaction is always spontaneous but proceeds faster at temperatures above 25. °C. A. AS is (pick one) v This reaction is spontaneous except below 63. °C but proceeds at a faster rate above AH is (pick one) v 117. °C. AS is (pick one) v AH is (pick one) v This reaction is always spontaneous, but proceeds faster at temperatures above 115. °C. AS is (pick one) v

Chemistry for Engineering Students

4th Edition

ISBN:9781337398909

Author:Lawrence S. Brown, Tom Holme

Publisher:Lawrence S. Brown, Tom Holme

Chapter10: Entropy And The Second Law Of Thermodynamics

Section: Chapter Questions

Problem 10.50PAE: For the reaction NO(g)+NO2(g)N2O3(g) , use tabulated thermodynamic data to calculate H and S. Then...

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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?
What determines Ssurr for a process? To calculate Ssurr at constant pressure and temperature, we use the following equation: Ssurr = H/T. Why does a minus sign appear in the equation, and why is Ssurr inversely proportional to temperature?
Consider two processes: sublimation of I2(s) and melting of I2(s) (Note: the latter process can occur at the same temperature but somewhat higher pressure). I2(s)I2(g)I2(s)I2(l) Is S positive or negative in these processes? In which of the processes will the magnitude of the entropy change be greater?
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?
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.)
Explain in your own words what is meant by the term entropy. Explain how both matter spread and energy spread are related to the concept of entropy.
The reaction CO2(g)+H2(g)CO(g)+H2O(g) is not spontaneous at room temperature but becomes spontaneous at a much higher temperature. What can you conclude from this about the signs of H and S , assuming that the enthalpy and entropy changes are not greatly affected by the temperature change? Explain your reasoning.
Thermite reactions have been used for welding metal parts such as railway rails and in metal refining. One such thermite reaction is Fe2O3(s)+2Al(s)Al2O3(s)+2Fe(s). Is the reaction spontaneous at room temperature under standard conditions? During the reaction, the surroundings absorb 851.8 kJ/mol of heat.
One statement of the second law of thermodynamics is that heat cannot be turned completely into work. Another is that the entropy of the universe always increases. How are these two statements related?
Consider the reaction CO(g)+H2O(g)CO2(g)+H2(g) Use the appropriate tables to calculate (a) G at 552C (b) K at 552C
Which contains greater entropy, a quantity of frozen benzene or the same quantity of liquid benzene at the same temperature? Explain in terms of the dispersal of energy in the substance.
Chemists and engineers who design nuclear power plants have to worry about high-temperature reactions because it is possible for water to decompose. (a) Under what conditions does this reaction occur spontaneously? 2H2O(g) 2H2(g) + O2(g) (b) Under conditions where the decomposition of water is spontaneous, do nuclear engineers have to worry about an oxygen/hydrogen explosion? Justify your answer.