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Ch.6 - Thermochemistry WorksheetSee 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
Nature of Energy
Kinetic & Potential Energy
First Law of Thermodynamics
Internal Energy
Endothermic & Exothermic Reactions
Heat Capacity
Constant-Pressure Calorimetry
Constant-Volume Calorimetry
Thermal Equilibrium
Thermochemical Equations
Formation Equations
Enthalpy of Formation
Hess's Law

The Enthalpy of Formation for an element is a key component in determining the enthalpy of reaction. 

Enthalpy of Formation

Concept #1: Enthalpy of Formation

Example #1: The reaction of methane with chlorine gas is illustrated by the reaction below:

Calculate the ∆Horxn if the standard enthalpies of formation for CH4 , CCl4 , and HCl are –74.87 kJ/mol, –139 kJ/mol and –92.31 kJ/mol respectively. 

Practice: The oxidation of ammonia is illustrated by the following equation: 

Calculate the enthalpy of reaction, ΔHRxn, based on the given standard heats of formation. 

Practice: Consider the following equation: 

2 ClF3(g) + 2 NH3(g) → 1 N2(g) + 6 HF (g) + 6 Cl2(g)  ΔHrxn = –1196 kJ

Determine the standard enthalpy of formation for chlorine trifluoride, ClF3