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Ch.15 - Chemical Equilibrium
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
All textbooksBrown 14th EditionCh.15 - Chemical EquilibriumProblem 69a
Chapter 15, Problem 69a

(a) Is the dissociation of fluorine molecules into atomic fluorine, F2(𝑔) β‡Œ 2 F(𝑔), an exothermic or endothermic process?

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1
Identify the type of reaction: The dissociation of fluorine molecules into atomic fluorine is a bond-breaking process.
Recall the general rule that breaking chemical bonds requires energy, while forming chemical bonds releases energy.
Determine the nature of the energy change: Since the reaction involves breaking the F-F bond in F2(g) to form atomic fluorine, energy is absorbed from the surroundings.
Conclude the type of thermodynamic process: If a reaction absorbs energy, it is considered endothermic.
State the answer: The dissociation of fluorine molecules into atomic fluorine is an endothermic process.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Dissociation Reactions

Dissociation reactions involve the breaking of bonds in a compound to form individual atoms or smaller molecules. In the case of fluorine, the reaction Fβ‚‚(g) β‡Œ 2 F(g) represents the dissociation of diatomic fluorine into two monatomic fluorine atoms. Understanding this process is crucial for determining the energy changes associated with the reaction.
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Percent Dissociation Example

Exothermic vs. Endothermic Processes

Exothermic processes release energy, usually in the form of heat, while endothermic processes absorb energy from the surroundings. The classification of a reaction as exothermic or endothermic can be determined by the energy changes that occur during bond breaking and formation. This distinction is essential for analyzing the thermodynamics of the dissociation of fluorine.
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Endothermic & Exothermic Reactions Example 2

Bond Energy

Bond energy is the amount of energy required to break a bond between two atoms. In the context of the dissociation of Fβ‚‚, the bond energy of the F-F bond must be considered to evaluate whether the process is exothermic or endothermic. If the energy required to break the bond is greater than the energy released when forming new bonds, the process is endothermic, and vice versa.
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Related Practice
Textbook Question
The water–gas shift reaction CO1g2 + H2O1g2Ξ” CO21g2 + H21g2 is used industrially to produce hydrogen. The reaction enthalpy is H = -41 kJ. (b) Could you increase the equilibrium yield of hydrogen by controlling the pressure of this reaction? If so would high or low pressure favor formation of H2(g)?
Textbook Question

(b) If the temperature is raised by 100 K, does the equilibrium constant for this reaction increase or decrease?

Textbook Question

Ozone, O3, decomposes to molecular oxygen in the stratosphere according to the reaction 2 O31g2Β‘3 O21g2. Would an increase in pressure favor the formation of ozone or of oxygen?

Textbook Question

Methanol (CH3OH) can be made by the reaction of CO with H2: CO(𝑔) + 2 H2(𝑔) β‡Œ CH3OH(𝑔) (c) To maximize the equilibrium yield of methanol, would you use a high or low pressure?