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with water in the presence of a suitable catalyst. C2 H4(g) + H2 O(g) ⟶ C2 H5 OH(l)
Using the data in the table in Appendix G, calculate ΔH° for the reaction.
84. The oxidation of the sugar glucose, C6H12O6, is described by the following equation:
C6 H12 O6(s) + 6O2(g) ⟶ 6CO2(g) + 6H2 O(l) ΔH = −2816 kJ
Chapter 5 Thermochemistry 279
The metabolism of glucose gives the same products, although the glucose reacts with oxygen in a series of steps in
the body.
(a) How much heat in kilojoules can be produced by the metabolism of 1.0 g of glucose?
(b) How many Calories can be produced by the metabolism of 1.0 g of glucose?
85. Propane, C3H8, is a hydrocarbon that is commonly used as a fuel.
(a) Write a balanced equation for the complete combustion of propane gas.
(b) Calculate the volume of air at 25 °C and 1.00 atmosphere that is needed to completely combust 25.0 grams of
propane. Assume that air is 21.0 percent O2 by volume. (Hint: we will see how to do this calculation in a later
chapter on gases—for now use the information that 1.00 L of air at 25 °C and 1.00 atm contains 0.275 g of O2 per
(c) The heat of combustion of propane is −2,219.2 kJ/mol. Calculate the heat of formation, ΔHf° of propane given
that ΔHf° of H2O(l) = −285.8 kJ/mol and ΔHf° of CO2(g) = −393.5 kJ/mol.
(d) Assuming that all of the heat released in burning 25.0 grams of propane is transferred to 4.00 kilograms of water,
calculate the increase in temperature of the water.
86. During a recent winter month in Sheboygan, Wisconsin, it was necessary to obtain 3500 kWh of heat provided
by a natural gas furnace with 89% efficiency to keep a small house warm (the efficiency of a gas furnace is the
percent of the heat produced by combustion that is transferred into the house).
(a) Assume that natural gas is pure methane and determine the volume of natural gas in cubic feet that was required
to heat the house. The average temperature of the natural gas was 56 °F; at this temperature and a pressure of 1 atm,
natural gas has a density of 0.681 g/L.
(b) How many gallons of LPG (liquefied petroleum gas) would be required to replace the natural gas used? Assume
the LPG is liquid propane [C3H8: density, 0.5318 g/mL; enthalpy of combustion, 2219 kJ/mol for the formation of
CO2(g) and H2O(l)] and the furnace used to burn the LPG has the same efficiency as the gas furnace.
(c) What mass of carbon dioxide is produced by combustion of the methane used to heat the house?
(d) What mass of water is produced by combustion of the methane used to heat the house?
(e) What volume of air is required to provide the oxygen for the combustion of the methane used to heat the house?
Air contains 23% oxygen by mass. The average density of air during the month was 1.22 g/L.
(f) How many kilowatt–hours (1 kWh = 3.6 × 106 J) of electricity would be required to provide the heat necessary
to heat the house? Note electricity is 100% efficient in producing heat inside a house.
(g) Although electricity is 100% efficient in producing heat inside a house, production and distribution of electricity
is not 100% efficient. The efficiency of production and distribution of electricity produced in a coal-fired power
plant is about 40%. A certain type of coal provides 2.26 kWh per pound upon combustion. What mass of this coal in
kilograms will be required to produce the electrical energy necessary to heat the house if the efficiency of generation
and distribution is 40%?
280 Chapter 5 Thermochemistry
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	1. About OpenStax College
	2. About OpenStax College’s Resources
	3. About Chemistry
	4. Atom-First Alternate Sequencing
	5. Ancillaries
	6. About Our Team
	Chapter 1. Essential Ideas
	1.1. Chemistry in Context*
	1.2. Phases and Classification of Matter*
	1.3. Physical and Chemical Properties*
	1.4. Measurements*
	1.5. Measurement Uncertainty, Accuracy, and Precision*
	1.6. Mathematical Treatment of Measurement Results*
	Chapter 2. Atoms, Molecules, and Ions
	2.1. Early Ideas in Atomic Theory*
	2.2. Evolution of Atomic Theory*
	2.3. Atomic Structure and Symbolism*
	2.4. Chemical Formulas*
	2.5. The Periodic Table*
	2.6. Molecular and Ionic Compounds*
	2.7. Chemical Nomenclature*
	Chapter 3. Composition of Substances and Solutions
	3.1. Formula Mass and the Mole Concept*
	3.2. Determining Empirical and Molecular Formulas*
	3.3. Molarity*
	3.4. Other Units for Solution Concentrations*
	Chapter 4. Stoichiometry of Chemical Reactions
	4.1. Writing and Balancing Chemical Equations*
	4.2. Classifying Chemical Reactions*
	4.3. Reaction Stoichiometry*
	4.4. Reaction Yields*
	4.5. Quantitative Chemical Analysis*
	Chapter 5. Thermochemistry
	5.1. Energy Basics*
	5.2. Calorimetry*
	5.3. Enthalpy*
	Chapter 6. Electronic Structure and Periodic Properties of Elements
	6.1. Electromagnetic Energy*
	6.2. The Bohr Model*
	6.3. Development of Quantum Theory*
	6.4. Electronic Structure of Atoms (Electron Configurations)*
	6.5. Periodic Variations in Element Properties*
	Chapter 7. Chemical Bonding and Molecular Geometry
	7.1. Ionic Bonding*
	7.2. Covalent Bonding*
	7.3. Lewis Symbols and Structures*
	7.4. Formal Charges and Resonance*
	7.5. Strengths of Ionic and Covalent Bonds*
	7.6. Molecular Structure and Polarity*
	Chapter 8. Advanced Theories of Covalent Bonding
	8.1. Valence Bond Theory*
	8.2. Hybrid Atomic Orbitals*
	8.3. Multiple Bonds*
	8.4. Molecular Orbital Theory*
	Chapter 9. Gases
	9.1. Gas Pressure*
	9.2. Relating Pressure, Volume, Amount, and Temperature: The Ideal Gas Law*
	9.3. Stoichiometry of Gaseous Substances, Mixtures, and Reactions*
	9.4. Effusion and Diffusion of Gases*
	9.5. The Kinetic-Molecular Theory*
	9.6. Non-Ideal Gas Behavior*
	Chapter 10. Liquids and Solids
	10.1. Intermolecular Forces*
	10.2. Properties of Liquids*
	10.3. Phase Transitions*
	10.4. Phase Diagrams*
	10.5. The Solid State of Matter*
	10.6. Lattice Structures in Crystalline Solids*
	Chapter 11. Solutions and Colloids
	11.1. The Dissolution Process*
	11.2. Electrolytes*
	11.3. Solubility*
	11.4. Colligative Properties*
	11.5. Colloids*
	Chapter 12. Kinetics
	12.1. Chemical Reaction Rates*
	12.2. Factors Affecting Reaction Rates*
	12.3. Rate Laws*
	12.4. Integrated Rate Laws*
	12.5. Collision Theory*
	12.6. Reaction Mechanisms*
	12.7. Catalysis*
	Chapter 13. Fundamental Equilibrium Concepts
	13.1. Chemical Equilibria*
	13.2. Equilibrium Constants*
	13.3. Shifting Equilibria: Le Châtelier’s Principle*
	13.4. Equilibrium Calculations*
	Chapter 14. Acid-Base Equilibria
	14.1. Brønsted-Lowry Acids and Bases*
	14.2. pH and pOH*
	14.3. Relative Strengths of Acids and Bases*
	14.4. Hydrolysis of Salt Solutions*
	14.5. Polyprotic Acids*
	14.6. Buffers*
	14.7. Acid-Base Titrations*
	Chapter 15. Equilibria of Other Reaction Classes
	15.1. Precipitation and Dissolution*
	15.2. Lewis Acids and Bases*
	15.3. Multiple Equilibria*
	Chapter 16. Thermodynamics
	16.1. Spontaneity*
	16.2. Entropy*
	16.3. The Second and Third Laws of Thermodynamics*
	16.4. Free Energy*
	Chapter 17. Electrochemistry
	17.1. Balancing Oxidation-Reduction Reactions*
	17.2. Galvanic Cells*
	17.3. Standard Reduction Potentials*
	17.4. The Nernst Equation*
	17.5. Batteries and Fuel Cells*
	17.6. Corrosion*
	17.7. Electrolysis*
	Chapter 18. Representative Metals, Metalloids, and Nonmetals
	18.1. Periodicity*
	18.2. Occurrence and Preparation of the Representative Metals*
	18.3. Structure and General Properties of the Metalloids*
	18.4. Structure and General Properties of the Nonmetals*
	18.5. Occurrence, Preparation, and Compounds of Hydrogen*
	18.6. Occurrence, Preparation, and Properties of Carbonates*
	18.7. Occurrence, Preparation, and Properties of Nitrogen*
	18.8. Occurrence, Preparation, and Properties of Phosphorus*
	18.9. Occurrence, Preparation,

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