Question 1

Which of the following best describes a Lewis acid?

Accepted Answer

A species that accepts an electron pair from another molecule.

Question 2

Consider the following reaction: $NH_3 + HCl \rightarrow NH_4^+ + Cl^-$. Which species acts as the Brønsted-Lowry base?

Accepted Answer

$NH_3$

Question 3

Which statement correctly relates $pK_a$ and acid strength?

Accepted Answer

A lower $pK_a$ value means a stronger acid.

Question 4

Which of the following factors most strongly stabilizes a conjugate base, thereby increasing the acidity of its parent acid?

Accepted Answer

Resonance delocalization

Question 5

Given the following acids, which is expected to be the strongest acid based on atomic size: $HF$, $HCl$, $HBr$, $HI$?

Accepted Answer

$HI$

Question 6

Which of the following statements about the inductive effect is correct?

Accepted Answer

The inductive effect stabilizes the conjugate base, making the acid stronger.

Question 7

Which of the following is the correct order of acid strength for the following carboxylic acids: acetic acid ($CH_3COOH$), trichloroacetic acid ($CCl_3COOH$)?

Accepted Answer

Trichloroacetic acid $>$ Acetic acid

Question 8

Which of the following bases is more reactive: $NH_2^-$ or $HO^-$?

Accepted Answer

$NH_2^-$

Question 9

Which of the following conjugate bases is most stable: $Cl^-$ or $H_2O$?

Accepted Answer

$Cl^-$

Question 10

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

Accepted Answer

Resonance increases the stability of the conjugate base, making the acid stronger.

Question 11

Which of the following is the correct order of base stability for the following carbanions: $sp^3$ ($CH_3^-$), $sp^2$ ($CH_2=CH^-$), $sp$ ($C\equiv CH^-$)?

Accepted Answer

$sp > sp^2 > sp^3$

Question 12

Which of the following is a correct example of a Lewis base?

Accepted Answer

$NH_3$

Question 13

In the reaction $H_2O + NH_3 \rightarrow OH^- + NH_4^+$, which species is the Brønsted-Lowry acid?

Accepted Answer

$H_2O$

Question 14

Which of the following is the most acidic proton in acetylene ($HC\equiv CH$) compared to ethylene ($H_2C=CH_2$) and ethane ($CH_3CH_3$)?

Accepted Answer

Acetylene

Question 15

Which of the following is the correct electron-pushing formalism for a Brønsted-Lowry acid-base reaction?

Accepted Answer

The arrow starts at the lone pair of the base and points to the acidic proton.

Question 16

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

Accepted Answer

Strong acids have stable conjugate bases.

Question 17

Which of the following is the correct order of priority for structural effects on acidity?

Accepted Answer

Atomic size > Resonance > Electronegativity > Induction > Hybridization

Question 18

Which of the following is a correct example of a nucleophile in a Lewis acid-base reaction?

Accepted Answer

$H_2O$

Question 19

Which of the following statements about $H_2$ as an acid is correct?

Accepted Answer

$H_2$ has a high $pK_a$ and is a weak acid.

Question 20

Which of the following best describes the role of $OH^-$ in the reaction $OH^- + CH_3COOH \rightarrow CH_3COO^- + H_2O$?

Accepted Answer

$OH^-$ acts as a Brønsted-Lowry base.

Chapter 4: Acids & Bases/Electron Flow – Organic Chemistry Study Notes

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