Concept explainers
(a)
Interpretation:
The given reactions need to be explained with the concept of work in
Concept Introduction :
The work is a transfer of energy from one system to another without change of entropy.
Where P is the pressure and
(b)
Interpretation:
The given reactions need to be explained with the concept of work in thermodynamics.
Concept Introduction :
The work is a transfer of energy from one system to another without change of entropy.
Where P is the pressure and
(c)
Interpretation:
The given reactions need to be explained with the concept of work in thermodynamics.
Concept Introduction :
The work is a transfer of energy from one system to another without change of entropy.
Where P is the pressure and
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Chemical Principles
- What is the sign of the work when a refrigerator compresses a gas (the system) to a liquid during the refrigeration cycle?arrow_forwardIdentify the sign of the work when a fuel-oxygen mixture (the system) burns, propelling an automobile (part of the surroundings).arrow_forwardWhen a rocket is launched, the burning gases are the source of the motion. If the system is the rocket (including fuel), what is the sign of the work?arrow_forward
- Dry 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_forwardThe 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_forwardHow is the sign of q, heat, defined? How does it relate to the total energy of the system?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_forwardIn which of the following systems is(are) work done by the surroundings on the system? Assume pressure and temperature are constant. a. 2SO2(g)+O2(g)2SO3(g) b.CO2(s)CO2(g) c. 4NH3(g)+7O2(g)4NO2(g)+6H2O(g) d.N2O4(g)2NO2(g) e.CaCO3(s)CaCO(s)+CO2(g)arrow_forwardWhen 1.000 g of gaseous butane, C4H10, is burned at 25C and 1.00 atm pressure, H2O(l) and CO2(g) are formed with the evolution of 49.50 kJ of heat. a Calculate the molar enthalpy of formation of butane. (Use enthalpy of formation data for H2O and CO2.) b Gf of butane is 17.2 kJ/mol. What is G for the combustion of 1 mol butane? c From a and b, calculate S for the combustion of 1 mol butane.arrow_forward
- A sample of benzene, C6H6, weighing 3.51 g was burned in an excess of oxygen in a bomb calorimeter. The temperature of the calorimeter rose from 25.00C to 37.18C. If the heat capacity of the calorimeter and contents was 12.05 kJ/C, what is the value of q for burning 1.00 mol of benzene at constant volume and 25.00C? The reaction is C6H6(l)+152O2(g)6CO2(g)+3H2O(l) Is q equal to U or H?arrow_forwardWhen 1.000 g of ethylene glycol, C2H6O2, is burned at 25C and 1.00 atmosphere pressure, H2O(l) and CO2(g) are formed with the evolution of 19.18 kJ of heat. a Calculate the molar enthalpy of formation of ethylene glycol. (It will be necessary to use data from Appendix C.) b Gf of ethylene glycol is 322.5 kJ/mol. What is G for the combustion of 1 mol ethylene glycol? c What is S for the combustion of 1 mol ethylene glycol?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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