Interpretation: the value of
Concept introduction:
In Spontaneous process, energy transfer from higher concentration to lower, or the energy is dispersed.
Entropy (S) is the quantity to measure the dispersal of energy in the spontaneous processes.
The equation for finding
Equation for
Equation for
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Chapter 18 Solutions
Chemistry & Chemical Reactivity
- Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted into metal from 99.90% to 99.99% purity by the Mond process. The primary reaction involved in the Mond process is Ni(s)+4CO(g)Ni(CO)4(g) a. Without referring to Appendix 4, predict the sign of S for the above reaction. Explain. b. The spontaneity of the above reaction is temperature-dependent. Predict the sign of Ssurr, for this reaction. Explain c. For Ni(CO)4(g), Hfo=607KJ/mol and S = 417 J/K mol at 298 K. Using these values and data in Appendix 4, calculate H and S for the above reaction. d. Calculate the temperature at which G = 0 (K = 1) for the above reaction, assuming that H and S do not depend on temperature. e. The first step of the Mood process involves equilibrating impure nickel with CO(g) and Ni(CO)4(g) at about 50C. The purpose of this step is to convert as much nickel as possible into the gas phase. Calculate the equilibrium constant for the above reaction at 50.C. f. In the second step of the Mood process, the gaseous Ni(CO)4 is isolated and heated to 227C. The purpose of this step is to deposit as much nickel as possible as pure solid (the reverse of the preceding reaction). Calculate the equilibrium constant for the preceding reaction at 227C. g. Why is temperature increased for the second step of the Mood process? h. The Mond process relies on the volatility of Ni(CO)4 for its success. Only pressures and temperatures at which Ni(CO)4 is a gas are useful. A recently developed variation of the Mood process carries out the first step at higher pressures and a temperature of l52C. Estimate the maximum pressure of Ni(CO)4(g) that can be attained before the gas will liquefy at 152C. The boiling point for Ni(CO)4 is 42C and the enthalpy of vaporization is 29.0 kJ/mol. [Hint: The phase change reaction and the corresponding equilibrium expression are Ni(CO)4(l)Ni(CO)4(g)K=PNi(CO)4 Ni(CO)4(g) will liquefy when the pressure of Ni(CO)4 is greater than the K value.]arrow_forwardSome 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?arrow_forwardCalculate H and G for the following reactions at 25C, using thermodynamic data from Appendix C; interpret the signs of H and G. a 2PbO(s)+N2(g)2Pb(s)+2NO(g)\ b CS2(l)+2H2O(l)CO2(g)+2H2S(g)arrow_forward
- 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 atmospherearrow_forwardPredict the sign of S, if possible, for each of the following reactions. If you cannot predict the sign for any reaction, state why. a HCl(g)+NH3(g)NH4Cl(s) b N2(g)+3H2(g)2NH3(g) c 2SO2(g)+O2(g)2SO3(g) d CH3OH(l)+32O2(g)CO2(g)+2H2O(g)arrow_forwardCalculate H and G for the following reactions at 25C, using thermodynamic data from Appendix C; interpret the signs of H and G. a Al2O3(s)+2Fe(s)Fe2O3(s)+2Al(s) b COCl2(g)+H2O(l)CO2(g)+2HCl(g)arrow_forward
- 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?arrow_forwardYeast can produce ethanol by the fermentation of glucose (C6H12O6), which is the basis for the production of most alcoholic beverages. C6H12O6(aq) 2 C2H5OH() + 2 CO2(g) Calculate rH, rS, and rG for the reaction at 25 C. Is the reaction product- or reactant-favored at equilibrium? In addition to the thermodynamic values in Appendix L, you will need the following data for C6H12O6(aq): fH = 1260.0 kl/mol; S = 289 J/K mol; and fG = 918.8 kl/mol.arrow_forwardCalculate the entropy change for each of these processes. thereby verifying the predictions made in Conceptual Exercise 16.4. (a) 2 CO2(g) 2 CO(g) + O2(g) (b) NaCl(s) NaCl(aq) (c) MgCO3(s) MgO(s) + CO2(g)arrow_forward
- The reaction shown below is involved in the refining of iron. (The table that follows provides all of the thermodynamic data you should need for this problem.) 2Fe2O3(s)+3C(s,graphite)4Fe(s)+3CO2(g) (a) Find H for the reaction. (b) S for the reaction above is 557.98 J/K. Find S° for Fe2O3(s). (c) Calculate G for the reaction at the standard temperature of 298 K. (There are two ways that you could do this.) (d) At what temperatures would this reaction be spontaneous? Compound Hf (kJ mol-1) S° (kJ mol-1) Gf (J mol-1 K-1) Fe2O3(s) -824.2 ? -742.2 C(s, graphite) 0 5.740 0 Fe(s) 0 27.3 0 CO2(g) -393.5 213.6 -394.4.83arrow_forwardIn the laboratory, POCl3 (phosphorus oxychloride) is used in the manufacture of phosphate esters, which are used in flame retardants and pesticides. It can be prepared by the following reaction at 25C: 2PCl3(g)+O2(g)2POCl3(g) H=572kJ;G=518.7kJ(a) Calculate S. Is the sign reasonable? (b) Calculate S for POCl3. (c) Calculate for POCl3.arrow_forwardAt 298 K, G = 70.52 kJ for the reaction 2NO(g) + O2(g) 2NO2(g) (a) Calculate _G at the same temperature when PNO = 1.0 104 atm, PO2=2.0103 atm, and PNO2=0.30 atm. (b) Under the conditions in part a, in which direction is the reaction spontaneous?arrow_forward
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