Using enthalpies of formation (Appendix C), calculate ΔH° for the following reaction at 25°C. Also calculate ΔS° for this reaction from standard entropies at 25°C. Use these values to calculate ΔG° for the reaction at this temperature.
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Chapter 18 Solutions
General Chemistry - Standalone book (MindTap Course List)
- Use the data in Appendix G to calculate the standard entropy change for H2(g) + CuO(s) H2O() + Cu(s)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_forwardThere are millions of organic compounds known, and new ones are being discovered or made at a rate of morethan 100,000 compounds per year. Organic compoundsburn readily in air at high temperatures to form carbondioxide and water. Several classes of organic compoundsare listed, with a simple example of each. Write a balanced chemical equation for the combustion in O2ofeach of these compounds, and then use the data inAppendix J to show that each reaction is product-favoredat room temperature. From these results, it is reasonable to hypothesize thatallorganic compounds are thermodynamically unstable inan oxygen atmosphere (that is, their room-temperaturereaction with O2(g) to form CO2(g) and H2O() isproduct-favored). If this hypothesis is true, how canorganic compounds exist on Earth?arrow_forward
- 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.)arrow_forwardThermodynamics provides a way to interpret everyday occurrences. If you live in northern climates, one common experience is that during early winter, snow falls but then melts when it hits the ground. Both the formation and the melting happen spontaneously. How can thermodynamics explain both of these seemingly opposed events?arrow_forwardDefine the following: a. spontaneous process b. entropy c. positional probability d. system e. surroundings f. universearrow_forward
- The molecular scale pictures below show snapshots of a strong acid at three different instants after it is added to water. Place the three pictures in the correct order so that they show the progress of the spontaneous process that takes place as the acid dissolves in the water. Explain your answer in terms of entropyarrow_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_forwardCoal is used as a fuel in some electric-generating plants. Coal is a complex material, but for simplicity we may consider it to be a form of carbon. The energy that can be derived from a fuel is sometimes compared with the enthalpy of the combustion reaction: C(s)+O2(g)CO2(g) Calculate the standard enthalpy change for this reaction at 25C. Actually, only a fraction of the heat from this reaction is available to produce electric energy. In electric generating plants, this reaction is used to generate heat for a steam engine, which turns the generator. Basically the steam engine is a type of heat engine in which steam enters the engine at high temperature (Th), work is done, and the steam then exits at a lower temperature (Tl). The maximum fraction, f, of heat available to produce useful energy depends on the difference between these temperatures (expressed in kelvins), f = (Th Tl)/Th. What is the maximum heat energy available for useful work from the combustion of 1.00 mol of C(s) to CO2(g)? (Assume the value of H calculated at 25C for the heat obtained in the generator.) It is possible to consider more efficient ways to obtain useful energy from a fuel. For example, methane can be burned in a fuel cell to generate electricity directly. The maximum useful energy obtained in these cases is the maximum work, which equals the free-energy change. Calculate the standard free-energy change for the combustion of 1.00 mol of C(s) to CO2(g). Compare this value with the maximum obtained with the heat engine described here.arrow_forward
- Yeast 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_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_forwardIndicate 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_forward
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