Ch.9 - Bonding & Molecular StructureWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Bond Energy

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Sections
Chemical Bonds
Lattice Energy
Lattice Energy Application
Born Haber Cycle
Dipole Moment
Lewis Dot Structure
Octet Rule
Formal Charge
Resonance Structures
Additional Practice
Bond Energy
Problem

Use the given bond enthalpies to estimate ∆H for the following reaction:

CH4(g) + 2 F2(g) → CF4(g) + 2 H2(g)

Bond enthalpies:

C−F 450. kJ mol−1    C−H 410. kJ mol−1     F−F 158 kJ mol−1     H−H 436 kJ mol−1

(A) 318 kJ 

(B) 716 kJ 

(C) -358 kJ 

(D) -716 kJ 

(E) -318 kJ

Solution

We’re being asked to calculate the enthalpy (ΔH) of reaction (in kJ) for the given reaction using the given bond enthalpies.

CH4(g) + 2 F2(g) → CF4(g) + 2 H2(g)


To calculate the ΔH°rxn using bond energies, we’re going to use the following equation:

H°rxn=Hbond reactants-Hbond products


Let’s first figure out what kind of bonds and how many moles are present in each reactants and products because the given bond energies are per mole.

Draw the structure of each compound.

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