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

Solution: Calculate the magnitude of the enthalpy change, and determine if the reaction is exothermic or endothermic for the following reaction: NH3 + 3F2 ⟶ NF3 + 3HFA. 870.9 kJ mol–1 , exothermic B. 870.9 kJ mol–1 , endothermic C. 1112 kJ mol–1 , exothermic D. 1112 kJ mol–1 , endothermic E. 290.3 kJ mol–1 , endothermic

Problem

Calculate the magnitude of the enthalpy change, and determine if the reaction is exothermic or endothermic for the following reaction: NH3 + 3F2 ⟶ NF3 + 3HF

A. 870.9 kJ mol–1 , exothermic 

B. 870.9 kJ mol–1 , endothermic 

C. 1112 kJ mol–1 , exothermic 

D. 1112 kJ mol–1 , endothermic 

E. 290.3 kJ mol–1 , endothermic

Solution

We are asked to calculate the magnitude of the enthalpy change, and determine if the reaction is exothermic or endothermic for reaction. 

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

ΔH°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.

Balanced Reaction NH3 + 3F2 ⟶ NF3 + 3HF

*always make sure that the given reaction is balanced


Draw the structure of each compound.

Reactants:

 NH3:


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