Videos
The industrial degreasing solvent methylene chloride, CH2Cl2, is prepared from methane by reaction with chlorine:
Use the following data to calculate ΔH° in kilojoules for the reaction:
Want to see the full answer?
Check out a sample textbook solution
Chapter 8 Solutions
General Chemistry: Atoms First
- The decomposition of ozone, O3, to oxygen, O2, is an exothermic reaction. What is the sign of q? If you were to touch a flask in which ozone is decomposing to oxygen, would you expect the flask to feel warm or cool?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_forward9.42 Why is enthalpy generally more useful than internal energy in the thermodynamics of real world systems?arrow_forward
- At 298 K, the standard enthalpies of formation for C2H2(g) and C6H6(l) are 227 kJ/mol and 49 kJ/mol, respectively. a. Calculate H for C6H6(l)3C2H2(g) b. Both acetylene (C2H2) and benzene (C6H6) can be used as fuels. Which compound would liberate more energy per gram when combusted in air?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_forwardHow is the sign of q, heat, defined? How does it relate to the total energy of the system?arrow_forward
- Gasohol, a mixture of gasoline and ethanol, C2H5OH, is used as automobile fuel. The alcohol releases energy in a combustion reaction with O2. C2H5OH(l)+3O2(g)2CO2(g)+3H2O(l) If 0.115 g ethanol evolves 3.62 kJ when burned at constant pressure, calculate the combustion enthalpy for ethanol.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_forwardA green plant synthesizes glucose by photosynthesis, as shown in the reaction: 6CO2(g) + 6H2O(l) C6H12O6(s) + 6O2(g) Animals use glucose as a source of energy: C6H12O6(s) + 6O2(g) 6CO2(g) + 6HO2(l) If we were to assume that both of these processes occur to the same extent in a cyclic process, what thermodynamic property must have a nonzero value?arrow_forward
- In a coffee-cup calorimeter, 1.60 g NH4NO3 is mixed with 75.0 g water at an initial temperature of 25.00C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.34C. Assuming the solution has a heat capacity of 4.18 J/C g and assuming no heat loss to the calorimeter, calculate the enthalpy change for the dissolution of NH4NO3 in units of kJ/mol.arrow_forwardThe combustion of methane can be represented as follows: a. Use the information given above to determine the value of H for the combustion of methane to form CO2(g) and 2H2O(l). b. What is Hf for an element in its standard state? Why is this? Use the figure above to support your answer. c. How does H for the reaction CO2(g) + 2H2O (1) CH4(g) + O2(g) compare to that of the combustion of methane? Why is this?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_forward
Chemistry: The Molecular ScienceChemistryISBN:9781285199047Author:John W. Moore, Conrad L. StanitskiPublisher:Cengage Learning
Chemistry: An Atoms First ApproachChemistryISBN:9781305079243Author:Steven S. Zumdahl, Susan A. ZumdahlPublisher:Cengage Learning
General Chemistry - Standalone book (MindTap Cour...ChemistryISBN:9781305580343Author:Steven D. Gammon, Ebbing, Darrell Ebbing, Steven D., Darrell; Gammon, Darrell Ebbing; Steven D. Gammon, Darrell D.; Gammon, Ebbing; Steven D. Gammon; DarrellPublisher:Cengage Learning
Chemistry & Chemical ReactivityChemistryISBN:9781337399074Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage Learning
Chemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage Learning
Chemistry: Principles and PracticeChemistryISBN:9780534420123Author:Daniel L. Reger, Scott R. Goode, David W. Ball, Edward MercerPublisher:Cengage Learning