Read the descriptions of physical or chemical changes in the table below. Then decide whether the change will be spontaneous, if you can. Change A solid absorbs heat and turns to a gas. A solid precipitates from a solution, absorbing heat as it does so. A gas expands without absorbing or releasing heat. Is this change spontaneous? Yes. No. Can't decide with information given. Yes. No. Can't decide with information given. Yes. No. Can't decide with information given.

Read the descriptions of physical or chemical changes in the table below. Then decide whether the change will be spontaneous, if you can. Change A solid absorbs heat and turns to a gas. A solid precipitates from a solution, absorbing heat as it does so. A gas expands without absorbing or releasing heat. Is this change spontaneous? Yes. No. Can't decide with information given. Yes. No. Can't decide with information given. Yes. No. Can't decide with information given.

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 10.99PAE: Thermodynamics provides a way to interpret everyday occurrences. If you live in northern climates,...

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9.20 State the first law of thermodynamics briefly in your own words.
Athletic trainers use instant ice packs that can be cooled quickly on demand. Squeezing the pact breaks an inner container, allowing two components to mix and react. This reaction makes the pack become cold. Describe the heat flow for this spontaneous process.
Thermodynamics 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?
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Nitrogen gas reacts with hydrogen gas to form ammonia gas .Consider the reaction between nitrogen and hydrogen as depicted below: a. Draw what the container will look like after the reaction has gone to completion. Assume a constant pressure of 1 atm. b. Is the sign of work positive or negative, or is the value of work equal to zero for the reaction? Explain your answer.
For each process, tell whether the entropy change of the system is positive or negative. Water vapor (the system) deposits as ice crystals on a cold windowpane. A can of carbonated beverage loses its fizz. (Consider the beverage but not the can as the system. What happens to the entropy of the dissolved gas?) A glassblower heats glass (the system) to its softening temperature.
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.)
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.
You have a large balloon containing 1.0 mol of gaseous water vapor at 80 C. How will each step affect the internal energy of the system? (a) The temperature of the system is raised to 90 C. (b) The vapor is condensed to a liquid, at 40 C.
What happens to the entropy of the universe during a spontaneous process?
Ethanol burns in air or oxygen according to the equation C2H5OH(l)+3O2(g)2CO2(g)+3H2O(g) Predict the sign of S for this reaction.