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Ch. 8 - Alkenes I: Properties and Electrophilic Additions
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
All textbooksMullins 1st EditionCh. 8 - Alkenes I: Properties and Electrophilic AdditionsProblem 1b(i)
Chapter 7, Problem 1b(i)

(i) Using bond dissociation energies, calculate ∆H° for the following reactions. [BDE for O―H = 110 kcal /mol.]
(b)

Verified step by step guidance
1
Step 1: Understand the concept of bond dissociation energy (BDE). BDE is the energy required to break a bond in a molecule into its individual atoms in the gas phase. It is used to estimate the enthalpy change (∆H°) of a reaction by considering the bonds broken and formed during the reaction.
Step 2: Write down the chemical equation for the reaction. Identify all the bonds that are broken in the reactants and all the bonds that are formed in the products.
Step 3: Use the given bond dissociation energy (BDE) values. For example, the BDE for O―H is provided as 110 kcal/mol. Look up or use additional BDE values for other bonds involved in the reaction if necessary.
Step 4: Calculate the total energy required to break the bonds in the reactants. This is done by summing the BDE values for all the bonds broken.
Step 5: Calculate the total energy released when new bonds are formed in the products. Subtract the energy released (from bond formation) from the energy required (from bond breaking) to determine the overall ∆H° for the reaction.

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Key Concepts

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

Bond Dissociation Energy (BDE)

Bond Dissociation Energy is the energy required to break a specific bond in a molecule, resulting in the formation of two radicals. It is a crucial concept in thermochemistry as it helps predict the stability of molecules and the energy changes during chemical reactions. Higher BDE values indicate stronger bonds, which require more energy to break.
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Enthalpy Change (∆H°)

Enthalpy change (∆H°) refers to the heat content change of a system at constant pressure during a chemical reaction. It can be calculated using bond dissociation energies by summing the energies of bonds broken and subtracting the energies of bonds formed. Understanding ∆H° is essential for predicting whether a reaction is exothermic or endothermic.
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Thermochemical Equations

Thermochemical equations represent the relationship between chemical reactions and the heat changes associated with them. They provide a way to quantify the energy changes in reactions, allowing chemists to calculate ∆H° using bond dissociation energies. These equations are vital for understanding reaction mechanisms and energy profiles.
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Breaking down the different terms of the Gibbs Free Energy equation.
Related Practice
Textbook Question

(a) Rank the following carbocations from least stable to most stable. (b) Which would you expect to form first? (c) Which would you expect to react most quickly with a bromide ion (Br⁻) ? [Carbocations, like radicals, are electron deficient.]

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Textbook Question

Given that A is more stable than B, draw a reaction coordinate diagram that rationalizes the fact that A forms more quickly than B in the following reaction.

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Textbook Question

Rationalize the fact that reaction A results in an unequal mixture of products, but reaction B yields an equal mixture of two products.

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