Question 1

Which of the following statements best describes a Lewis acid?

Accepted Answer

A substance that accepts an electron pair.

Question 2

Which of the following compounds is expected to be the strongest acid based on the effect of electronegativity?

Accepted Answer

$$\mathrm{HF}$$

Question 3

Given the following acids: $$\mathrm{H_2S}$$, $$\mathrm{HCl}$$, $$\mathrm{HBr}$$, and $$\mathrm{HI}$$, which one is the strongest acid and why?

Accepted Answer

$$\mathrm{HI}$$, because the larger iodide ion stabilizes the negative charge best.

Question 4

Which of the following statements about the Henderson-Hasselbalch equation is correct?

Accepted Answer

It relates the pH, $$pK_a$$, and the ratio of conjugate base to acid concentrations.

Question 5

A solution contains acetic acid ($$pK_a = 4.76) $$and its conjugate base. If the pH of the solution is 5.76, what is the ratio $$\left( \frac{[A^-]}{[HA]} \right)$$?

Accepted Answer

$$10$$

Question 6

Which of the following structural changes would most likely increase the acidity of acetic acid?

Accepted Answer

Replacing a hydrogen on the methyl group with a chlorine atom.

Question 7

Which of the following is the conjugate base of $$\mathrm{$$HCO_3$$^-}$$?

Accepted Answer

$$\mathrm{CO_3$^{2-}}$$

Question 8

Which of the following best explains why carboxylic acids are stronger acids than alcohols?

Accepted Answer

Carboxylic acids have resonance stabilization of their conjugate base.

Question 9

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

Accepted Answer

The stronger the acid, the weaker its conjugate base.

Question 10

Which of the following compounds is expected to have the highest $$pK_a$$ value?

Accepted Answer

Methylamine

Question 11

Which of the following best describes the effect of increasing 's character' in hybridization on acid strength?

Accepted Answer

Increasing 's character' increases acid strength due to a shorter, stronger bond.

Question 12

Which of the following is a correct application of the Bronsted-Lowry definition?

Accepted Answer

$$\mathrm{HCl}$$ acts as an acid by donating a proton to $$\mathrm{H_2O}.$$

Question 13

Which of the following statements about amines is correct?

Accepted Answer

Amines are the most common organic bases.

Question 14

Which of the following best explains why the acidity of hydrohalic acids increases from $$\mathrm{HF} to$$ $$\mathrm{HI}$$?

Accepted Answer

Bond strength decreases down the group, making it easier to lose a proton.

Question 15

Which of the following is the correct conjugate acid of $$\mathrm{NH_2$^-}$$?

Accepted Answer

$$\mathrm{NH_3$}$$

Question 16

A solution contains benzoic acid ($$pK_a = 4.2) $$and the pH is adjusted to 2.2. Which form will predominate?

Accepted Answer

The acid form ($$\mathrm{C_6H_5COOH})$$

Question 17

Which of the following best describes the effect of resonance on acid strength?

Accepted Answer

Resonance increases acid strength by stabilizing the conjugate base.

Question 18

Which of the following is a Lewis base?

Accepted Answer

$$\mathrm{CH_3O^-}$$

Question 19

Which of the following statements is true regarding protonated compounds?

Accepted Answer

Protonated compounds are stronger acids with $$pK_a$$ values typically less than 1.

Question 20

Which of the following best describes the effect of an electron-withdrawing group on acid strength?

Accepted Answer

It increases acid strength by stabilizing the conjugate base.

Chapter 4: Acids and Bases – Organic Chemistry Study Notes

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