Chemistry: An Atoms First Approach
2nd Edition
ISBN: 9781305079243
Author: Steven S. Zumdahl, Susan A. Zumdahl
Publisher: Cengage Learning
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Textbook Question
Chapter 7, Problem 8RQ
What is Hess’s law? When a reaction is reversed, what happens to the sign and magnitude of ∆H for that reversed reaction? When the coefficients in a balanced reaction are multiplied by a factor n, what happens to the sign and magnitude of ∆H for that multiplied reaction?
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Chapter 7 Solutions
Chemistry: An Atoms First Approach
Ch. 7 - Define the following terms: potential energy,...Ch. 7 - Consider the following potential energy diagrams...Ch. 7 - What is the first law of thermodynamics? How can a...Ch. 7 - When a gas expands, what is the sign of w? Why?...Ch. 7 - Prob. 5RQCh. 7 - High-quality audio amplifiers generate large...Ch. 7 - Explain how calorimetry works to calculate H or E...Ch. 7 - What is Hesss law? When a reaction is reversed,...Ch. 7 - Define the standard enthalpy of formation. What...Ch. 7 - Prob. 1ALQ
Ch. 7 - Prob. 2ALQCh. 7 - A fire is started in a fireplace by striking a...Ch. 7 - Liquid water turns to ice. Is this process...Ch. 7 - Prob. 5ALQCh. 7 - Prob. 6ALQCh. 7 - Consider 5.5 L of a gas at a pressure of 3.0 atm...Ch. 7 - Explain why oceanfront areas generally have...Ch. 7 - Hesss law is really just another statement of the...Ch. 7 - Prob. 10ALQCh. 7 - Prob. 11QCh. 7 - Prob. 12QCh. 7 - Assuming gasoline is pure C8H18(l), predict the...Ch. 7 - Prob. 14QCh. 7 - The enthalpy change for the reaction...Ch. 7 - For the reaction HgO(s)Hg(l)+12O2(g),H=+90.7KJ: a....Ch. 7 - Prob. 17QCh. 7 - The enthalpy change for a reaction is a state...Ch. 7 - Standard enthalpies of formation are relative...Ch. 7 - The combustion of methane can be represented as...Ch. 7 - Prob. 21QCh. 7 - Prob. 22QCh. 7 - Prob. 23QCh. 7 - Prob. 24QCh. 7 - Prob. 25ECh. 7 - Prob. 26ECh. 7 - Consider the following diagram when answering the...Ch. 7 - Consider the accompanying diagram. Ball A is...Ch. 7 - A gas absorbs 45 kJ of heat and does 29 kJ of...Ch. 7 - A system releases 125 kJ of heat while 104 kJ of...Ch. 7 - Calculate E for each of the following. a. q = 47...Ch. 7 - A system undergoes a process consisting of the...Ch. 7 - If the internal energy of a thermodynamic system...Ch. 7 - Calculate the internal energy change for each of...Ch. 7 - A sample of an ideal gas at 15.0 atm and 10.0 L is...Ch. 7 - Prob. 36ECh. 7 - Consider a mixture of air and gasoline vapor in a...Ch. 7 - As a system increases in volume, it absorbs 52.5 J...Ch. 7 - A balloon filled with 39.1 moles of helium has a...Ch. 7 - Prob. 40ECh. 7 - One of the components of polluted air is NO. It is...Ch. 7 - Prob. 42ECh. 7 - Are the following processes exothermic or...Ch. 7 - Are the following processes exothermic or...Ch. 7 - The overall reaction in a commercial heat pack can...Ch. 7 - Consider the following reaction:...Ch. 7 - Consider the combustion of propane:...Ch. 7 - Consider the following reaction:...Ch. 7 - Prob. 49ECh. 7 - The specific heat capacity of silver is 0.24 J/Cg....Ch. 7 - A 500-g sample of one of the substances listed in...Ch. 7 - Prob. 52ECh. 7 - A 30.0-g sample of water at 280. K is mixed with...Ch. 7 - A biology experiment requires the preparation of a...Ch. 7 - A 5.00-g sample of aluminum pellets (specific heat...Ch. 7 - Hydrogen gives off 120. J/g of energy when burned...Ch. 7 - Prob. 57ECh. 7 - A 110.-g sample of copper (specific heat capacity...Ch. 7 - In a coffee-cup calorimeter, 50.0 mL of 0.100 M...Ch. 7 - In a coffee-cup calorimeter, 100.0 mL of 1.0 M...Ch. 7 - A coffee-cup calorimeter initially contains 125 g...Ch. 7 - In a coffee-cup calorimeter, 1.60 g NH4NO3 is...Ch. 7 - Consider the dissolution of CaCl2:...Ch. 7 - Consider the reaction...Ch. 7 - The heat capacity of a bomb calorimeter was...Ch. 7 - The combustion of 0.1584 g benzoic acid increases...Ch. 7 - The enthalpy of combustion of solid carbon to form...Ch. 7 - Combustion reactions involve reacting a substance...Ch. 7 - Given the following data calculate H for the...Ch. 7 - Given the following data...Ch. 7 - Prob. 71ECh. 7 - Calculate H for the reaction...Ch. 7 - Given the following data...Ch. 7 - Given the following data...Ch. 7 - Give the definition of the standard enthalpy of...Ch. 7 - Write reactions for which the enthalpy change will...Ch. 7 - Prob. 77ECh. 7 - Use the values of Hf in Appendix 4 to calculate H...Ch. 7 - The Ostwald process for the commercial production...Ch. 7 - Calculate H for each of the following reactions...Ch. 7 - The reusable booster rockets of the space shuttle...Ch. 7 - The space shuttle Orbiter utilizes the oxidation...Ch. 7 - Consider the reaction...Ch. 7 - The standard enthalpy of combustion of ethene gas,...Ch. 7 - Water gas is produced from the reaction of steam...Ch. 7 - Prob. 86ECh. 7 - Prob. 87ECh. 7 - Prob. 88ECh. 7 - Some automobiles and buses have been equipped to...Ch. 7 - The complete combustion of acetylene, C2H2(g),...Ch. 7 - Prob. 91AECh. 7 - One way to lose weight is to exercise! Walking...Ch. 7 - Three gas-phase reactions were run in a...Ch. 7 - Nitrogen gas reacts with hydrogen gas to form...Ch. 7 - Combustion of table sugar produces CO2(g) and H2O(...Ch. 7 - Prob. 96AECh. 7 - Consider the following cyclic process carried out...Ch. 7 - Calculate H for the reaction...Ch. 7 - The enthalpy of neutralization for the reaction of...Ch. 7 - Prob. 100AECh. 7 - If a student performs an endothermic reaction in a...Ch. 7 - In a bomb calorimeter, the reaction vessel is...Ch. 7 - The bomb calorimeter in Exercise 102 is filled...Ch. 7 - Prob. 104AECh. 7 - Consider the following equations:...Ch. 7 - Prob. 106AECh. 7 - At 298 K, the standard enthalpies of formation for...Ch. 7 - Prob. 108AECh. 7 - A sample of nickel is heated to 99.8C and placed...Ch. 7 - Quinone is an important type of molecule that is...Ch. 7 - Calculate H for each of the following reactions,...Ch. 7 - Compare your answers from parts a and b of...Ch. 7 - Compare your answer from Exercise 72 of Chapter 3...Ch. 7 - Consider a balloon filled with helium at the...Ch. 7 - Prob. 115CWPCh. 7 - Prob. 116CWPCh. 7 - Prob. 117CWPCh. 7 - A swimming pool, 10.0 m by 4.0 m, is filled with...Ch. 7 - Prob. 119CWPCh. 7 - Calculate H for the reaction...Ch. 7 - Which of the following substances have an enthalpy...Ch. 7 - Consider 2.00 moles of an ideal gas that are taken...Ch. 7 - For the process H2O(l)H2O(g) at 298 K and 1.0 atm,...Ch. 7 - The sun supplies energy at a rate of about 1.0...Ch. 7 - Prob. 125CPCh. 7 - The standard enthalpies of formation for S(g),...Ch. 7 - Use the following standard enthalpies of formation...Ch. 7 - The standard enthalpy of formation for N2H4(g) is...Ch. 7 - The standard enthalpy of formation for NO(g) is...Ch. 7 - A piece of chocolate cake contains about 400...Ch. 7 - You have a l.00-mole sample of water at 30.C and...Ch. 7 - A 500.0-g sample of an element at 195C is dropped...Ch. 7 - A cubic piece of uranium metal (specific heat...Ch. 7 - On Easter Sunday, April 3, 1983, nitric acid...Ch. 7 - Using data from Chapter 2, calculate the change in...Ch. 7 - In Exercise 89 in Chapter 3, the Lewis structures...Ch. 7 - A gaseous hydrocarbon reacts completely with...
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- 9.42 Why is enthalpy generally more useful than internal energy in the thermodynamics of real world systems?arrow_forwardUnder what circumstances is the heat of a process equal to the enthalpy change for the process?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_forward
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- How is the sign of q, heat, defined? How does it relate to the total energy of the system?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_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_forward
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