Q: Which of the following best describes the effect of atomic size on acid strength for binary hydrides (e.g., $HF$, $HCl$, $HBr$, $HI$)?

Acid strength increases as the size of the atom bonded to hydrogen increases.

Question 1

Which of the following best explains why water has a much higher boiling point than methane, even though both are small molecules?

Accepted Answer

Water forms strong hydrogen bonds between its molecules, while methane only exhibits London dispersion forces.

Question 2

Which of the following statements about resonance structures is correct?

Accepted Answer

The actual structure of a molecule with resonance is a hybrid of all possible resonance forms.

Question 3

Given the following acids: acetic acid ($CH_3COOH$), hydrochloric acid ($HCl$), and phenol ($C_6H_5OH$), which is the strongest acid in water and why?

Accepted Answer

Hydrochloric acid, because it completely dissociates in water.

Question 4

Which of the following best describes the relationship between $pK_a$ and acid strength?

Accepted Answer

A lower $pK_a$ value indicates a stronger acid.

Question 5

Which of the following molecules would have the highest boiling point, assuming similar molar masses?

Accepted Answer

A molecule capable of hydrogen bonding.

Question 6

Which of the following is the correct Lewis structure for the ammonium ion ($NH_4^+$)?

Accepted Answer

A nitrogen atom single-bonded to four hydrogen atoms, with a positive charge on the nitrogen.

Question 7

Which of the following best explains why $HF$ is a weaker acid than $HCl$ in aqueous solution?

Accepted Answer

$HF$ forms stronger hydrogen bonds, making it less likely to dissociate.

Question 8

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

Accepted Answer

It accepts a proton ($H^+$) from another species.

Question 9

Which of the following factors increases the acidity of a molecule?

Accepted Answer

Increased resonance stabilization of the conjugate base.

Question 10

A student is asked to rank the following compounds by increasing boiling point: methane ($CH_4$), methanol ($CH_3OH$), and chloromethane ($CH_3Cl$). Which is the correct order?

Accepted Answer

$CH_4 < CH_3Cl < CH_3OH$

Question 11

Which of the following best describes the effect of atomic size on acid strength for binary hydrides (e.g., $HF$, $HCl$, $HBr$, $HI$)?

Accepted Answer

Acid strength increases as the size of the atom bonded to hydrogen increases.

Question 12

Which of the following is the correct mathematical relationship for $pK_a$?

Accepted Answer

$pK_a = -\log_{10} K_a$

Question 13

Which of the following statements about intermolecular forces is correct?

Accepted Answer

London dispersion forces are present in all molecules, regardless of polarity.

Question 14

Which of the following best explains why $CH_3COOH$ (acetic acid) is a stronger acid than $CH_3CH_2OH$ (ethanol)?

Accepted Answer

The conjugate base of acetic acid is resonance stabilized.

Question 15

Which of the following is the correct order of increasing acid strength for the following species: $H_2O$, $CH_3OH$, $CH_3COOH$?

Accepted Answer

$CH_3OH < H_2O < CH_3COOH$

Question 16

Which of the following best describes the role of a Lewis base in a chemical reaction?

Accepted Answer

A Lewis base donates an electron pair to form a covalent bond.

Question 17

A solution has a $[H_3O^+]$ concentration of $1 	imes 10^{-4}$ M. What is the pH of the solution?

Accepted Answer

$pH = 4$

Question 18

Which of the following is a correct statement about the relationship between electronegativity and acid strength?

Accepted Answer

Higher electronegativity of the atom bonded to hydrogen increases acid strength.

Question 19

Which of the following best explains why $NH_3$ (ammonia) can act as a base in water?

Accepted Answer

Ammonia has a lone pair of electrons that can accept a proton from water.

Question 20

Which of the following is the correct expression for the equilibrium constant ($K_{eq}$) for the reaction $HA \rightleftharpoons H^+ + A^-$?

Accepted Answer

$K_{eq} = \frac{[H^+][A^-]}{[HA]}$

General Chemistry: Acids, Bases, and Intermolecular Forces – Study Guide

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