Question 1

Which of the following statements best describes the relationship between acid strength and pK$_a$ value?

Accepted Answer

The stronger the acid, the smaller its pK$_a$ value.

Question 2

Given the following reaction: $\mathrm{CH_3COOH} + \mathrm{NH_3} \rightleftharpoons \mathrm{CH_3COO^-} + \mathrm{NH_4^+}$, which direction does equilibrium favor?

Accepted Answer

Formation of $\mathrm{CH_3COO^-}$ and $\mathrm{NH_4^+}$ (products)

Question 3

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

Accepted Answer

Hydrogen fluoride ($\mathrm{HF}$)

Question 4

A buffer solution is prepared using acetic acid ($\mathrm{CH_3COOH}$) and sodium acetate ($\mathrm{CH_3COO^-Na^+}$). Which equation best describes the pH of this buffer?

Accepted Answer

$\mathrm{pH = pK_a - log\left(\frac{[CH_3COOH]}{[CH_3COO^-]}\right)}$

Question 5

Which factor most directly explains why carboxylic acids are stronger acids than alcohols?

Accepted Answer

Carboxylic acids have delocalized electrons in their conjugate base.

Question 6

What is the correct expression for the acid dissociation constant ($K_a$) for the reaction $\mathrm{HA + H_2O \rightleftharpoons H_3O^+ + A^-}$?

Accepted Answer

$K_a = \frac{[H_3O^+][A^-]}{[HA]}$

Question 7

Which of the following statements about the conjugate base of a strong acid is true?

Accepted Answer

It is a weak base.

Question 8

If the pK$_a$ of acetic acid is 4.76 and the pK$_a$ of ammonia is 9.4, what is the equilibrium constant ($K_{eq}$) for the reaction $\mathrm{CH_3COOH + NH_3 \rightleftharpoons CH_3COO^- + NH_4^+}$?

Question 9

Which of the following best explains why methyl alcohol ($\mathrm{CH_3OH}$) is a stronger acid than methylamine ($\mathrm{CH_3NH_2}$)?

Accepted Answer

Oxygen is more electronegative than nitrogen.

Question 10

Which of the following is a correct statement about the effect of substituents on acid strength?

Accepted Answer

The closer the electronegative substituent is to the acidic proton, the stronger the acid.

Question 11

Which of the following species is neutral in its acidic form and charged in its basic form?

Accepted Answer

Alcohol

Question 12

Which of the following is a Lewis acid?

Accepted Answer

Aluminum chloride ($\mathrm{AlCl_3}$)

Question 13

Which of the following factors does NOT increase acid strength?

Question 14

At a pH equal to the pK$_a$ of a compound, what is the ratio of acidic form to basic form?

Accepted Answer

1:1

Question 15

Which of the following best describes the role of a buffer solution?

Accepted Answer

It maintains a nearly constant pH when small amounts of acid or base are added.

Question 16

Which of the following is the correct formula for calculating pH?

Accepted Answer

$\mathrm{pH = -log[H^+]}$

Question 17

Which of the following statements about electron delocalization is true?

Accepted Answer

Delocalized electrons result from p orbital overlap with adjacent orbitals.

Question 18

Which of the following is the correct relationship between hybridization and acidity for carbon acids?

Accepted Answer

sp > sp$^2$ > sp$^3$ (increasing acidity)

Acids and Bases: Central Concepts in Organic Chemistry

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