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 entropy AS. Note: if you have not been given enough information to decide a sign, select the "unknown" option. reaction observations conclusions AH is A The reaction is never spontaneous. AS is AH is B This reaction is always spontaneous, but proceeds faster at temperatures above -23. °C. AS is AH is с This reaction is spontaneous only above 67. °C but proceeds at a slower rate below 200. °C. AS is X ✓ (pick one) positive negative unknown [{PTOR OITOT (pick one) (pick one) v (pick one) S

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 entropy AS. Note: if you have not been given enough information to decide a sign, select the "unknown" option. reaction observations conclusions AH is A The reaction is never spontaneous. AS is AH is B This reaction is always spontaneous, but proceeds faster at temperatures above -23. °C. AS is AH is с This reaction is spontaneous only above 67. °C but proceeds at a slower rate below 200. °C. AS is X ✓ (pick one) positive negative unknown [{PTOR OITOT (pick one) (pick one) v (pick one) S

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 10.51PAE: 10.51 The combustion of acetylene was used in welder's torches for many years because it produces a...

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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.
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.
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How does the second law of thermodynamics explain a spontaneous change in a system that becomes more ordered when that process is exothermic?
The standard molar entropy of iodine vapor, I2(g), is 260.7 J Kl mol-1 and the standard molar enthalpy of formation is 62.4 kJ/mol. a) Calculate the entropy change for vaporization of 1 mol of solid iodine (use data from Table 16.1 or Appendix J). b) Calculate the enthalpy change for sublimation of iodine. c) Assuming that rSdoes not change with temperature, estimate the temperature at which iodine would sublime (change directly from solid to gas).
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