Interpretation:
By using the given information, the maximum work obtained from
Concept introduction:
Standard free energy change:
Standard free energy change is measured by subtracting the product of temperature and standard entropy change from the standard enthalpy change of a system.
To calculate: The value of
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Chapter 18 Solutions
General Chemistry - Standalone book (MindTap Course List)
- 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_forward2. In which of the following reactions is there a significant transfer of energy as work from the system to the surroundings? This occurs if there is a change in the number of moles of gases. C(s) + O2(g) → CO2(g) CH4(g) + 2 O2(g) → CO2g) + 2 H2O(g) 2 C(s) + O2(g) → 2 CO(g) 2 Mg(s) + O2(g) → 2 MgO(s)arrow_forwardA pot of cold water is heated on a stove, and when the water boils, a fresh egg is placed in the water to cook. Describe the events that are occurring in terms of the zeroth law of thermodynamics.arrow_forward
- Calculatethe work on the system whena piston is compressed by a pressure of 1780torr from 3.55 L to1.00 L.arrow_forwardThe formation of aluminum oxide from its elements is highly exothermic. If 2.70 g Al metal is burned in pure O2 to give A12O3, calculate how much thermal energy is evolved in the process (at constant pressure).arrow_forwardA bottle of soda has a head space containing 25.0 mL of CO2 gas at 4.2 atm pressure when the soda is at 4.4C. The bottle is opened slowly, letting the excess pressure escape. Howmuch work does the escaping CO2 do if the ambient pressure is 1.0 atm? Assume that the temperature remains constant.arrow_forward
- The statement Energycan beneithercreatednor destroyedis sometimes used as an equivalent statement of the first law of thermodynamics. There areinaccuracies to the statement, however. Restate it tomake it less inaccurate.arrow_forward9.42 Why is enthalpy generally more useful than internal energy in the thermodynamics of real world systems?arrow_forwardDry ice is solid carbon dioxide; it vaporizes at room temperature and normal pressures to the gas. Suppose you put 21.5 g of dry ice in a vessel fitted with a piston (similar to the one in Figure 6.9 but with the weight replaced by the atmosphere), and it vaporizes completely to the gas, pushing the piston upward until its pressure and temperature equal those of the surrounding atmosphere at 24.0C and 751 mmHg. Calculate the work done by the gas in expanding against the atmosphere. Neglect the volume of the solid carbon dioxide, which is very small in comparison to the volume of the gas phase.arrow_forward
- 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.arrow_forwardWhat are the two ways that a final chemical state of a system can be more probable than its initial state?arrow_forwardCalculatethe work performed by a person whoexertsa force of 30 NN = newtonstomove abox 30metersif the force were a exactly parallel to the directionofmovement, and b45to thedirection of movement. Do the relative magnitudesmakesense?arrow_forward
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