Chapter 6 organic chem Flashcards
Heat energy
change in a reaction
Enthalpy
(ΔH)
Exothermic
Releases heat (ΔH negative)
Endothermic
Absorbs heat (ΔH positive).
Exothermic Energy
Reactants higher than products.
Activation energy peak.
ΔH is negative.
What is Entropy (ΔS)?
Measure of disorder or randomness.
More space or moles = higher entropy.
What is Gibbs Free Energy (ΔG) and its formula?
Predicts if a reaction is spontaneous.
Formula: ΔG = ΔH - TΔS.
Negative ΔG: Spontaneous.
Positive ΔG: Non-spontaneous.
Nucleophile
Electron giver (negative or lone pairs)
Electrophile
Electron taker (positive or electron-poor)
Draw a nucleophilic attack using curved arrows.
Arrow starts at lone pair or negative charge on nucleophile.
Arrow ends at positive or electron-poor part of electrophile.
What is a transition state?
High-energy, short-lived peak on an energy diagram.
Cannot be observed.
What is an intermediate?
Lower energy, temporary species in a reaction.
Can be observed.
What is a carbocation rearrangement?
Shifting H or CH3 group to make a carbocation more stable.
Stability order: Tertiary > Secondary > Primary.
four curved arrow patterns
Nucleophilic attack.
Loss of a leaving group.
Proton transfer.
Rearrangements.
How do you identify a good leaving group?
Stable on its own after leaving.
Common examples: Cl⁻, Br⁻, I⁻
What makes a reaction reversible?
Good leaving group and small energy difference.
Draw: Double-headed arrow (⇌).
What makes a reaction irreversible?
Poor leaving group or large energy difference.
Draw: Single-headed arrow (→).
What is the Hammond Postulate?
Transition state resembles nearest stable species.
Exothermic: Looks like reactants.
Endothermic: Looks like products.
What is the rate law formula?
Rate = k[A]^x[B]^y.
X and Y: Order of reaction for each reactant.
What is activation energy (E_a)
Energy needed to start a reaction.
Lower E_a: Faster reaction.
How to identify localized vs. delocalized lone pairs?
Localized: Stays on one atom.
Delocalized: Part of resonance (p-orbital overlap).
What is Le Châtelier’s Principle?
System shifts to oppose changes in concentration, temperature, or pressure.
Key formula: ΔH
ΔH = BDE (bonds broken) - BDE (bonds formed).
Key formula: ΔG = ?
ΔG = -RT ln K_eq.
Negative ΔG: Product-favored equilibrium.
