Textbook Question
If hydrogen were used as a fuel, it could be burned according to this reaction: H2(g) + 1/2 O2(g) → H2O(g) Use average bond energies to calculate ΔHrxn for this reaction.
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Ch.10 - Chemical Bonding I: The Lewis Model
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217
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Table of contents
- Ch.1 - Matter, Measurement & Problem Solving90
- Ch.2 - Atoms & Elements94
- Ch.3 - Molecules and Compounds103
- Ch.4 - Chemical Reactions and Chemical Quantities46
- Ch.5 - Introduction to Solutions and Aqueous Solutions65
- Ch.6 - Gases100
- Ch.7 - Thermochemistry85
- Ch.8 - The Quantum-Mechanical Model of the Atom51
- Ch.9 - Periodic Properties of the Elements79
- Ch.10 - Chemical Bonding I: The Lewis Model70
- Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory68
- Ch.12 - Liquids, Solids & Intermolecular Forces44
- Ch.13 - Solids & Modern Materials42
- Ch.14 - Solutions77
- Ch.15 - Chemical Kinetics88
- Ch.16 - Chemical Equilibrium57
- Ch.17 - Acids and Bases121
- Ch.18 - Aqueous Ionic Equilibrium126
- Ch.19 - Free Energy & Thermodynamics80
- Ch.20 - Electrochemistry87
- Ch.21 - Radioactivity & Nuclear Chemistry61
- Ch.22 - Organic Chemistry114
Chapter 10, Problem 111c
If hydrogen were used as a fuel, it could be burned according to this reaction: H2(g) + 1/2 O2(g) → H2O(g) Which fuel yields more energy per mole?
Verified step by step guidance1
Identify the reaction given and the products formed. In this case, the reaction is the combustion of hydrogen gas (H2) with oxygen gas (O2) to form water vapor (H2O).
Understand that the energy yield from a reaction can be determined by looking at the enthalpy change (ΔH) of the reaction. For combustion reactions, this is typically exothermic, meaning it releases energy.
Consult standard enthalpy of formation tables or reliable chemical data sources to find the ΔH values for the reactants and products involved in the reaction.
Calculate the net energy yield by using the formula: ΔH = ΣΔHproducts - ΣΔHreactants. This will give the energy released or absorbed per mole of reaction.
Compare the energy yield of hydrogen combustion with that of other common fuels (like methane, propane, etc.) using their respective ΔH values for combustion to determine which fuel yields more energy per mole.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Combustion Reactions
Combustion reactions involve the chemical reaction of a fuel with an oxidant, typically oxygen, resulting in the release of energy in the form of heat and light. In the case of hydrogen, the reaction with oxygen produces water vapor and releases energy, making it a highly efficient fuel. Understanding the stoichiometry of combustion reactions is essential for calculating energy yields.
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Combustion Apparatus
Enthalpy of Combustion
The enthalpy of combustion is the amount of energy released when one mole of a substance is completely burned in oxygen. This value is crucial for comparing the energy output of different fuels. For hydrogen, the enthalpy of combustion is significantly high, indicating that it releases a large amount of energy per mole when combusted.
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Molar Mass and Energy Density
Molar mass refers to the mass of one mole of a substance, which affects the energy density of fuels. Energy density is the amount of energy stored in a given volume or mass of fuel. When comparing fuels, it is important to consider both the molar mass and the energy released per mole to determine which fuel is more efficient in terms of energy output.
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Related Practice
Textbook Question
If hydrogen were used as a fuel, it could be burned according to this reaction: H2(g) + 1/2 O2(g) → H2O(g) Which fuel yields more energy per gram?
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Textbook Question
Free radicals are important in many environmentally significant reactions (see the Chemistry in the Environment box on free radicals in this chapter). For example, photochemical smog— smog that results from the action of sunlight on air pollutants— forms in part by these two steps:
The product of this reaction, ozone, is a pollutant in the lower atmosphere. (Upper atmospheric ozone is a natural part of the atmosphere that protects life on Earth from ultraviolet light.) Ozone is an eye and lung irritant and also accelerates the weathering of rubber products. Rewrite the given reactions using the Lewis structure of each reactant and product. Identify the free radicals.
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Textbook Question
The azide ion, N3-, is a symmetrical ion, all of whose contributing resonance structures have formal charges. Draw three important contributing structures for this ion.
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Textbook Question
Draw the Lewis structure for each compound. c. H3AsO4
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Textbook Question
If hydrogen were used as a fuel, it could be burned according to this reaction: H2(g) + 1/2 O2(g) → H2O(g) Use average bond energies to calculate ΔHrxn for the combustion of methane (CH4).
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