Organic Chemistry Third Edition Chapter 3 - Acids and Bases (Video Notes)

41 practice flashcards covering Bronsted-Lowry definitions, curved arrows, pKa, ARIO factors, solvent leveling effects, Lewis acids/bases, counter ions, and predicting equilibrium positions based on notes from Organic Chemistry 3e, Chapter 3.

What is the Brønsted-Lowry definition of an acid?

Acids donate a proton.

What is the Brønsted-Lowry definition of a base?

Bases accept a proton.

What is a conjugate acid in a Brønsted-Lowry reaction?

The species formed when a base accepts a proton.

What is a conjugate base in a Brønsted-Lowry reaction?

The species formed when an acid donates a proton.

In reaction mechanisms, what do curved arrows describe?

The flow of electron density and the movement of electrons.

How do curved arrows in mechanisms differ from resonance arrows?

They depict actual movement of electrons, not just resonance structures.

In the simple acid-base mechanism discussed, how many arrow pairs move?

Two arrows (two electron pairs move).

What core skill does the course emphasize when drawing mechanisms?

Correctly using curved arrows to show acid-base (proton transfer) steps.

What is Ka a measure of?

The acid dissociation constant in water.

What is pKa?

The negative logarithm of Ka; pKa = -log Ka.

If an acid is strong, is Ka typically greater or smaller than 1?

Ka is greater than 1.

What does a smaller pKa value indicate about acidity?

Stronger acid.

How can pKa values be used to compare acid strengths quantitatively?

Smaller pKa means stronger acid; larger pKa means weaker.

What is the relationship between acid strength and the stability of its conjugate base?

Stronger acid has a weaker conjugate base.

In predicting equilibrium, which side is favored when comparing pKa values?

The side with the weaker acid (higher pKa).

If ΔpKa is large (e.g., ≈34), what does that imply about product formation?

Approximately 10^34 more products than reactants.

What does ARIO stand for?

Atom, Resonance, Induction, Orbital.

In ARIO, what does the 'Atom' factor refer to?

The type/size of the atom bearing the charge; larger atoms stabilize negative charge.

When comparing different atoms, which stabilizes negative charge more, a larger atom or a smaller one?

A larger atom stabilizes the negative charge more.

If two atoms are in the same period, which stabilizes the negative charge better?

The more electronegative atom.

What is the role of resonance in ARIO?

Delocalizes the negative charge over multiple atoms, increasing stability.

What is the role of induction in ARIO?

Electron-withdrawing groups stabilize the negative charge; proximity matters.

How does the orbital type affect stability of a negative charge?

More s-character (sp > sp2 > sp3) stabilizes the charge.

What is the typical ARIO priority order?

Atom, then Resonance, then Induction, then Orbital.

Are ARIO guidelines always reliable?

They are a useful guideline, but there are exceptions.

Between ethanol and propylene, which is more acidic and why?

Ethanol is more acidic; the oxygen atom stabilizes the conjugate base; ARIO supports this (solvent effects can modify outcomes).

What is the leveling effect in water?

Water limits acid/base strength: acids stronger than H3O+ cannot be used in water and bases stronger than OH− cannot be used in water.

What is a solvent’s general role in acid-base reactions (leveling aside)?

Solvents surround reactants and facilitate collisions without reacting themselves.

What is the Lewis definition of a Lewis acid?

A species that accepts a pair of electrons.

What is the Lewis definition of a Lewis base?

A species that donates a pair of electrons.

Are Brønsted-Lowry acids/bases also Lewis acids/bases?

Yes; they are also Lewis acids/bases.

Can there be Lewis acid–base reactions that cannot be classified by Brønsted-Lowry?

Yes; some reactions fit only the Lewis definition.

What is a counter ion, and what is another name for it?

A spectator ion that balances charge; also called a counterion.

What is the practical effect of counterions in reaction drawings?

They balance the overall charge but are often omitted for simplicity.

What skill is mentioned in 3.5 Choosing a Reagent?

Choosing an acid from Table 3.1 that could effectively protonate a given molecule.

What skill is mentioned in 3.5 Predicting Equilibrium Position?

Predicting which side is favored using pKa values or base stability.

What is the leveling effect specifically when using water as solvent?

Strong acids are neutralized to H3O+ and strong bases are neutralized to OH−, limiting actual reagents.

What does ARIO say about the role of conjugate base stability?

A stronger acid produces a more stable conjugate base.

What does resonance stabilization do to a conjugate base’s stability?

Delocalizes negative charge, often increasing stability.

Why does the solvent affect acidity beyond ARIO predictions?

Solvent stabilization of ions (solvation) can override ARIO ordering in practice.

What is a key example of induction affecting acidity?

Electron-withdrawing groups near the negative charge stabilize the conjugate base.

How does orbital s-character relate to acidity?

Greater s-character in the orbital holding the charge makes it more stable.

Why might tert-butoxide be less acidic than ethoxide in some solvents?

Steric hindrance reduces solvation, decreasing stabilization of the conjugate base.

What is a practical takeaway about predicting acid–base outcomes from these notes?

Use pKa values and base conjugate stability, with ARIO as a guideline plus solvent effects.

What is a common example used to illustrate acidity differences by conjugate-base stability?

Carboxylic acids with resonance-stabilized conjugate bases (two oxgyens).

Why are carboxylic acids generally stronger acids than alcohols?

Their conjugate bases are resonance-stabilized across two oxygens.

What is the main difference between a Brønsted-Lowry and a Lewis view when comparing acids and bases?

BL focuses on proton transfer; Lewis focuses on electron pair donation/acceptance.

What does the ‘practice with SkillBuilders’ indicate about learning acid-base chemistry?

Practice reinforces mechanism drawing, pKa analysis, and equilibrium prediction.