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PHYSICAL CHEMISTRY-STUDENT SOLN.MAN.
- 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.arrow_forwardConsider the reaction of 2 mol H2(g) at 25C and 1 atm with 1 mol O2(g) at the same temperature and pressure to produce liquid water at these conditions. If this reaction is run in a controlled way to generate work, what is the maximum useful work that can be obtained? How much entropy is produced in this case?arrow_forwardWhich 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.arrow_forward
- Consider the reaction of 1 mol H2(g) at 25C and 1 atm with 1 mol Br2(l) at the same temperature and pressure to produce gaseous HBr at these conditions. If this reaction is run in a controlled way to generate work, what is the maximum useful work that can be obtained? How much entropy is produced in this case?arrow_forwardFor each of the following processes, identify the systemand the surroundings. Identify those processes that arespontaneous. For each spontaneous process, identify theconstraint that has been removed to enable the process to occur: Ammonium nitrate dissolves in water. Hydrogen and oxygen explode in a closed bomb. A rubber band is rapidly extended by a hangingweight. The gas in a chamber is slowly compressed by aweighted piston. A glass shatters on the floor.arrow_forwardFor each process, predict whether entropy increases or decreases, and explain how you arrived at your prediction. 2 CO2(g) → 2 CO(g) + O2(g) NaCl(s) → NaCl(aq) MgCO3(s) → MgO(s) + CO2(g)arrow_forward
- The decomposition of diamond to graphite [C(diamond) C(graphite)] is thermodynamically favored, but occurs slowly at room temperature. a. Use fG values from Appendix L to calculate rG and Keq for the reaction under standard conditions and 298.15 K. b. Use fH and S values from Appendix L to estimate rG and Keq for the reaction at 1000 K. Assume that enthalpy and entropy values are valid at these temperatures. Does heating shift the equilibrium toward the formation of diamond or graphite? c. Why is the formation of diamond favored at high pressures? d. The phase diagram shows that diamond is thermodynamically favored over graphite at 20,000 atmospheres pressure (about 2 GPa) at room temperature. Why is this conversion actually done at much higher temperatures and pressures?arrow_forwardWhat is the sign of the standard Gibbs free-energy change at low temperatures and at high temperatures for the explosive decomposition of TNT? Use your knowledge of TNT and the chemical equation, particularly the phases, to answer this question. (Thermodynamic data for TNT are not in Appendix G.) 2C7H5N3O6(s) 3N2(g) + 5H2O() + 7C(s) + 7CO(g)arrow_forwardWhat 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?arrow_forward
- The standard molar entropy of methanol vapor, CH3OH(g), is 239.8 J K1 mol-1. (a) Calculate the entropy change for the vaporization of 1 mol methanol (use data from Table 16.1 or Appendix J). (b) Calculate the enthalpy of vaporization of methanol, assuming that rS doesnt depend on temperature and taking the boiling point of methanol to be 64.6C.arrow_forwardTetrachloromethane (carbon tetrachloride), CCl4, has a normal boiling point of 76.7C and an enthalpy of vaporization, Hvap, of 29.82 kJ/mol. Estimate the entropy of vaporization, Svap. Estimate the free energy of vaporization, Gvap, at 25C.arrow_forwardSolid NH4NO3 is placed in a beaker containing water at 25 C. When the solid has completely dissolved, the temperature of the solution is 23.5 C. (a) Was the process exothermic or endothermic? (b) Was the process spontaneous? (c) Did the entropy of the system increase? (d) Did the entropy of the universe increase?arrow_forward
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