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Questions and Answers
A reaction in which elements are added to a starting material is classified as a(n) _____ reaction.
A reaction in which elements are added to a starting material is classified as a(n) _____ reaction.
addition
For this type of reaction to occur, the starting material must have a _____ bond to which elements can be added.
For this type of reaction to occur, the starting material must have a _____ bond to which elements can be added.
pi
A reaction in which an atom or group of atoms is replaced by another atom or group of atoms is classified as a(n) _____ reaction.
A reaction in which an atom or group of atoms is replaced by another atom or group of atoms is classified as a(n) _____ reaction.
substitution
A detailed description of the steps in a reaction is called a reaction _____.
A detailed description of the steps in a reaction is called a reaction _____.
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In a(n) ___________ elements of the starting material are 'lost' and a new ________ bond is formed.
In a(n) ___________ elements of the starting material are 'lost' and a new ________ bond is formed.
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Which of the following statements correctly describe the conventions used when writing equations for organic reactions? (Select all that apply)
Which of the following statements correctly describe the conventions used when writing equations for organic reactions? (Select all that apply)
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Select all the statements that correctly describe the changes occurring in addition reactions.
Select all the statements that correctly describe the changes occurring in addition reactions.
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Which of the following options correctly describe the characteristics of an elimination reaction? (Select all that apply)
Which of the following options correctly describe the characteristics of an elimination reaction? (Select all that apply)
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Which of the following statements are correct about a reaction mechanism? (Select all that apply)
Which of the following statements are correct about a reaction mechanism? (Select all that apply)
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What is heterolytic bond cleavage?
What is heterolytic bond cleavage?
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What is homolytic bond cleavage?
What is homolytic bond cleavage?
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___________ generates charged reactive intermediates, whereas __________ generates uncharged reactive intermediates.
___________ generates charged reactive intermediates, whereas __________ generates uncharged reactive intermediates.
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Since bonds are broken and formed in the same step, the reaction is said to be _____.
Since bonds are broken and formed in the same step, the reaction is said to be _____.
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A stepwise reaction involves the formation of at least one reactive _____, which then goes on to form the product(s).
A stepwise reaction involves the formation of at least one reactive _____, which then goes on to form the product(s).
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A half-headed (fishhook) curved arrow is used to show the movement of a ______ electron(s), whereas a full-headed arrow shows the movement of a ______ electron(s).
A half-headed (fishhook) curved arrow is used to show the movement of a ______ electron(s), whereas a full-headed arrow shows the movement of a ______ electron(s).
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Heterolytic bond cleavage _____. (Select all the options that complete the sentence correctly.)
Heterolytic bond cleavage _____. (Select all the options that complete the sentence correctly.)
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If a bond C-Z undergoes heterolytic cleavage and both bonding electrons move to the carbon atom, the intermediate formed will have a ______ charge on the carbon atom and will be called a ______.
If a bond C-Z undergoes heterolytic cleavage and both bonding electrons move to the carbon atom, the intermediate formed will have a ______ charge on the carbon atom and will be called a ______.
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A reaction intermediate that has a lone pair and a negative charge on a carbon atom is called a(n) ______, whereas an intermediate with a positive charge on a carbon atom is called a(n) ______.
A reaction intermediate that has a lone pair and a negative charge on a carbon atom is called a(n) ______, whereas an intermediate with a positive charge on a carbon atom is called a(n) ______.
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Which of the following options correctly describe the reactivity of the different reaction intermediates formed by bond cleavage? (Select all that apply)
Which of the following options correctly describe the reactivity of the different reaction intermediates formed by bond cleavage? (Select all that apply)
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What is a polar reaction?
What is a polar reaction?
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A carbocation or a carbon radical will act as a(n)
A carbocation or a carbon radical will act as a(n)
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A carbanion will act as a(n)
A carbanion will act as a(n)
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An electron-deficient carbon atom is present in
An electron-deficient carbon atom is present in
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A lone pair of electrons on a carbon atom is present in
A lone pair of electrons on a carbon atom is present in
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Which of the following options correctly describe bond formation? (Select all that apply)
Which of the following options correctly describe bond formation? (Select all that apply)
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The bond dissociation energy is the energy needed to _____ cleave a(n) _____ bond.
The bond dissociation energy is the energy needed to _____ cleave a(n) _____ bond.
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When two radicals bond,
When two radicals bond,
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When two oppositely charged ions bond,
When two oppositely charged ions bond,
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Which of the following options correctly describe ΔHo for a reaction? (Select all that apply)
Which of the following options correctly describe ΔHo for a reaction? (Select all that apply)
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If ΔHo for a particular reaction is positive, which statements correctly describe the reaction? (Select all that apply)
If ΔHo for a particular reaction is positive, which statements correctly describe the reaction? (Select all that apply)
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Which of the following options correctly interpret the bond dissociation energy for the H-F bond, which is 569 kJ/mol? (Select all that apply)
Which of the following options correctly interpret the bond dissociation energy for the H-F bond, which is 569 kJ/mol? (Select all that apply)
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The energy required to homolytically cleave a covalent bond is called the bond _____ energy.
The energy required to homolytically cleave a covalent bond is called the bond _____ energy.
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Which of the following options correctly describe bond strength, bond dissociation energy, and their periodic trends? (Select all that apply)
Which of the following options correctly describe bond strength, bond dissociation energy, and their periodic trends? (Select all that apply)
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If ΔHo for a reaction is negative, the reaction is _____.
If ΔHo for a reaction is negative, the reaction is _____.
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The energy released in forming bonds is _____ than the energy needed to break bonds, and the bonds formed in the product(s) are _____ than the bonds broken in the starting material(s).
The energy released in forming bonds is _____ than the energy needed to break bonds, and the bonds formed in the product(s) are _____ than the bonds broken in the starting material(s).
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Energy is absorbed
Energy is absorbed
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Energy is released
Energy is released
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Bond breaking
Bond breaking
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Bond formation
Bond formation
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Which of the following options correctly describe how to calculate ΔHo for a reaction using bond dissociation energies? (Select all that apply)
Which of the following options correctly describe how to calculate ΔHo for a reaction using bond dissociation energies? (Select all that apply)
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The C-O bond in CH3OH has a _____ bond dissociation energy than the C-S bond in CH3SH because C-O bond is _____ and _____.
The C-O bond in CH3OH has a _____ bond dissociation energy than the C-S bond in CH3SH because C-O bond is _____ and _____.
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Reaction rate
Reaction rate
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Reaction energies and position of equilibrium
Reaction energies and position of equilibrium
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Study Notes
Reaction Types
- Addition Reaction: Involves adding elements to a starting material that has a π bond, resulting in the formation of new bonds.
- Substitution Reaction: An atom or a group of atoms is replaced by another atom or group of atoms.
- Elimination Reaction: Characterized by the loss of elements from the starting material and formation of a new π bond. Typically involves breaking two σ bonds.
Reaction Mechanisms
- Mechanism: A detailed account of the sequence of steps in a reaction, providing insight into bond formation and cleavage.
- Concerted Reaction: A one-step process where the starting material directly converts to products.
- Stepwise Reaction: Involves multiple steps, often generating reactive intermediates.
Bond Cleavage
- Heterolytic Bond Cleavage: Both electrons from the bond move to one atom, often resulting in charged intermediates.
- Homolytic Bond Cleavage: Electrons split evenly between the two bonded atoms, forming radical intermediates.
Intermediates and Reactivity
- Carbocations: Positively charged carbon intermediates that act as electrophiles due to electron deficiency.
- Carbanions: Negatively charged carbon intermediates that act as nucleophiles because of their lone pair of electrons.
- Radicals: Unstable species with an incomplete octet, often behave as electrophiles.
Nucleophiles and Electrophiles
- Nucleophile: A species that donates an electron pair to an electrophile in a reaction.
- Electrophile: A species that accepts an electron pair, often represented by carbocations or carbon radicals.
Bond Formation and Energy
- Bond Formation: Always releases energy; when two radicals bond, each contributes one bonding electron.
- Bond Dissociation Energy: Energy required to homolytically cleave a bond. Increases across a period and correlates with bond strength.
- Exothermic vs. Endothermic: A negative ΔHº indicates an exothermic reaction where energy released in bond formation exceeds the energy required to break bonds.
Thermodynamics of Reactions
- ΔHº: Representing heat of reaction; positive values indicate endothermic processes while negative values indicate exothermic processes.
- Calculating ΔHº: Involves summing bond dissociation energies for bonds broken (positive) and formed (negative).
Periodic Trends in Bond Strength
- Bond strength increases from left to right across the periodic table.
- Larger atoms generally exhibit lower bond strength and bond dissociation energy.
Summary of Key Points
- Each reaction type has distinct characteristics and implications in organic chemistry.
- Understanding mechanisms and intermediates is crucial in predicting reaction outcomes.
- Energetics play a significant role in determining whether a reaction is favorable or not.
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Description
This quiz covers various types of chemical reactions, including addition, substitution, and elimination reactions. It also explores the mechanisms behind these reactions, highlighting concerted and stepwise processes, as well as different bond cleavage methods. Test your knowledge of these fundamental concepts in chemistry.
