Question 1

Which of the following statements best describes a Bronsted-Lowry acid?

Accepted Answer

A substance that donates a proton ($$\mathrm{H^+}).$$

Question 2

In the reaction $$\mathrm{CH_3COOH + H_2O \rightarrow CH_3COO^- + H_3O^+}$$, which species is the conjugate base?

Accepted Answer

$$\mathrm{CH_3COO^-}$$

Question 3

Which curved arrow in a single-step acid/base reaction mechanism represents the breaking of a bond?

Accepted Answer

The arrow that starts at the bond between the acid and its proton and points to the acid.

Question 4

Given the acid dissociation constant $$K_a$$ for an acid is $$10^{-5}$$, what is its $$pK_a$$?

Accepted Answer

$$pK_a = 5$$

Question 5

Which factor is most important when comparing the ability of oxygen and carbon to stabilize a negative charge in their conjugate bases?

Accepted Answer

Electronegativity

Question 6

Which compound is expected to be more acidic: ethanol ($$pK_a \approx 16) or $$acetylene ($$pK_a \approx 25$$)?

Accepted Answer

Ethanol, because the negative charge is on oxygen, which is more electronegative than carbon.

Question 7

Which of the following statements about resonance and acidity is correct?

Accepted Answer

Resonance stabilizes the negative charge on a conjugate base, making the acid stronger.

Question 8

Trichloroacetic acid ($$pK_a \approx 0.7) is $$much more acidic than acetic acid ($$pK_a \approx 4.75) $$because:

Accepted Answer

The chlorine atoms inductively withdraw electron density, stabilizing the conjugate base.

Question 9

Which orbital holds a negative charge most stably?

Accepted Answer

$$sp$$

Question 10

Which of the following is the correct order of importance for the ARIO factors when assessing acidity?

Accepted Answer

Atom, Resonance, Induction, Orbital

Question 11

If the $$pK_a of $$the acid on the left is 16 and the $$pK_a of $$the acid on the right is 38, which direction will the equilibrium favor?

Accepted Answer

Toward the right (products), because the acid on the right is weaker.

Question 12

Why can't acids stronger than $$\mathrm{H_3O^+} be $$used in water as a solvent?

Accepted Answer

Water will react with the strong acid, leveling its strength to that of $$\mathrm{H_3O^+}.$$

Question 13

Which of the following is a Lewis acid but NOT a Bronsted-Lowry acid?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 14

Which of the following best explains why tert-butanol is less acidic than ethanol?

Accepted Answer

Tert-butoxide is less solvated due to steric hindrance, making its conjugate base less stable.

Question 15

Which of the following is true about the relationship between acid strength and conjugate base strength?

Accepted Answer

The stronger the acid, the weaker its conjugate base.

Question 16

Which of the following is NOT a factor in the ARIO acronym for assessing conjugate base stability?

Accepted Answer

Solvation

Question 17

A student wants to use $$\mathrm{$$NaNH_2$$} as a $$base in water. Why is this not appropriate?

Accepted Answer

$$\mathrm{$$NaNH_2$$} is $$stronger than $$\mathrm{OH^-}$$ and will react with water.

Question 18

Which of the following best describes a Lewis base?

Accepted Answer

A species that donates a pair of electrons.

Question 19

Which of the following is a correct application of $$pK_a$$ values to predict equilibrium position?

Accepted Answer

Equilibrium favors the side with the weaker acid (higher $$pK_a).$$

Organic Chemistry Chapter 3: Acids and Bases (Study Notes)

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