Interpretation:
The minimum value for the change in entropy
Concept Introduction:
In
The equation given below helps us to calculate the change in free energy in a system.
Where,
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Chemistry: Atoms First
- There 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_forwardThe 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 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_forward
- Use the data in Appendix G to calculate the standard entropy change for H2(g) + CuO(s) H2O() + Cu(s)arrow_forwardHow is the sign of q, heat, defined? How does it relate to the total energy of the system?arrow_forwardFor 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_forward
- Coal 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_forwardThe combustion of acetylene, C2H2, is a spontaneous reaction given by the equation 2C2H2(g)+5O2(g)4CO2(g)+2H2O(l) As expected for a combustion, the reaction is exothermic. What is the sign of H? What do you expect for the sign of S? Explain the spontaneity of the reaction in terms of the enthalpy and entropy changes.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_forward
- What is meant by the standard free-energy change G for a reaction? What is meant by the standard free energy of formation Gf of a substance?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_forwardDefine the following: a. spontaneous process b. entropy c. positional probability d. system e. surroundings f. universearrow_forward
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