Textbook Question
Write the Lewis structure for each molecule. d. CH4
Ch.9 - Chemical Bonding I: The Lewis Model
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831
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Table of contents
- Ch.1 - Matter, Measurement & Problem Solving136
- Ch.2 - Atoms & Elements112
- Ch.3 - Molecules, Compounds & Chemical Equations159
- Ch.4 - Chemical Quantities & Aqueous Reactions140
- Ch.5 - Gases118
- Ch.6 - Thermochemistry106
- Ch.7 - Quantum-Mechanical Model of the Atom62
- Ch.8 - Periodic Properties of the Elements103
- Ch.9 - Chemical Bonding I: The Lewis Model104
- Ch.10 - Chemical Bonding II: Molecular Shapes & Valence Bond Theory89
- Ch.11 - Liquids, Solids & Intermolecular Forces73
- Ch.12 - Solids and Modern Material59
- Ch.13 - Solutions110
- Ch.14 - Chemical Kinetics140
- Ch.15 - Chemical Equilibrium78
- Ch.16 - Acids and Bases155
- Ch.17 - Aqueous Ionic Equilibrium176
- Ch.18 - Free Energy and Thermodynamics108
- Ch.19 - Electrochemistry118
- Ch.20 - Radioactivity and Nuclear Chemistry82
- Ch.21 - Organic Chemistry150
Chapter 9, Problem 48
Use the Born–Haber cycle and data from Appendix IIB and Table 9.3 to calculate the lattice energy of CaO. (ΔHsub for calcium is 178 kJ/mol; IE1 and IE2 for calcium are 590 kJ/mol and 1145 kJ/mol, respectively; EA1 and EA2 for O are -141 kJ/mol and 744 kJ/mol, respectively.)
Verified step by step guidance1
Identify all the relevant energies provided and required for the Born-Haber cycle: sublimation energy of calcium (ΔHsub), first and second ionization energies of calcium (IE1, IE2), and the first and second electron affinities of oxygen (EA1, EA2).
Write the Born-Haber cycle for the formation of CaO. Start with solid calcium and diatomic oxygen gas as reactants, and proceed through the steps of sublimation, ionization, electron affinity, and formation of solid CaO.
Apply Hess's Law to the cycle, which states that the total enthalpy change for a reaction is the sum of all changes and is independent of the pathway taken. Set up an equation where the sum of the enthalpy changes for sublimation, ionization, electron affinity, and formation equals the enthalpy of formation of CaO.
Substitute the given values into the equation. Include the sublimation energy of calcium, the first and second ionization energies of calcium, and the first and second electron affinities of oxygen.
Solve the equation for the lattice energy of CaO, which is the unknown in the cycle. Rearrange the equation to isolate the lattice energy on one side.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Born-Haber Cycle
The Born-Haber cycle is a thermodynamic cycle that relates the lattice energy of an ionic compound to other thermodynamic quantities. It involves a series of steps, including the sublimation of the metal, ionization energy, electron affinity, and the formation of the ionic solid from its gaseous ions. This cycle allows for the calculation of lattice energy by applying Hess's law, which states that the total enthalpy change is the sum of the changes in each step.
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Born Haber Cycle
Lattice Energy
Lattice energy is the energy released when gaseous ions combine to form an ionic solid, or the energy required to separate one mole of an ionic solid into its gaseous ions. It is a measure of the strength of the forces between the ions in an ionic compound. Higher lattice energy indicates stronger ionic bonds, which typically results in higher melting points and greater stability of the compound.
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Ionization Energy and Electron Affinity
Ionization energy is the energy required to remove an electron from an atom or ion in the gas phase, while electron affinity is the energy change that occurs when an electron is added to a neutral atom in the gas phase. These concepts are crucial in the Born-Haber cycle as they help quantify the energy changes associated with forming cations and anions, which are essential for calculating the overall lattice energy of ionic compounds like CaO.
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Related Practice
Textbook Question
Use the Born–Haber cycle and data from Appendix IIB, Chapter 8 and this chapter to calculate the lattice energy of KCl. (ΔHsub for potassium is 89.0 kJ/mol.)
Textbook Question
The lattice energy of CsF is -744 kJ/mol, whereas that of BaO is -3029 kJ/mol. Explain this large difference in lattice energy.
Textbook Question
Write the Lewis structure for each molecule. a. PH3 b. SCl2 c. HI
Textbook Question
Rubidium iodide has a lattice energy of -617 kJ/mol, while potassium bromide has a lattice energy of -671 kJ/mol. Why is the lattice energy of potassium bromide more exothermic than the lattice energy of rubidium iodide?