Q: Which of the following is the correct order of increasing strength of intermolecular forces?

London dispersion < dipole-dipole < hydrogen bonding

Question 1

A sample of gas occupies $31.0\ \mathrm{mL}$ at $372\ \mathrm{K}$ and $1.25\ \mathrm{atm}$. What will be the volume of the gas if the pressure is increased to $3.00\ \mathrm{atm}$ and the temperature is decreased to $298\ \mathrm{K}$, assuming the amount of gas remains constant?

Accepted Answer

$10.2\ \mathrm{mL}$

Question 2

Which of the following statements best explains why water ($\mathrm{H_2O}$) has a much higher boiling point than methane ($\mathrm{CH_4}$)?

Accepted Answer

Water molecules form hydrogen bonds, which are much stronger than the London dispersion forces present in methane.

Question 3

A $0.250\ \mathrm{mol}$ sample of $\mathrm{CO_2}$ gas is confined in a $5.00\ \mathrm{L}$ container at $27.0^\circ\mathrm{C}$. What is the pressure of the gas? ($R = 0.0821\ \mathrm{L\cdot atm\cdot mol^{-1}\cdot K^{-1}}$)

Accepted Answer

$1.23\ \mathrm{atm}$

Question 4

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

$\mathrm{CO_2}$

Question 5

A $12.0\ \mathrm{L}$ gas sample at $298\ \mathrm{K}$ is transferred to a $0.58\ \mathrm{atm}$ container. If the initial pressure was $1.2\ \mathrm{atm}$, what is the final volume of the gas, assuming temperature is constant?

Accepted Answer

$24.8\ \mathrm{L}$

Question 6

Which of the following best describes the relationship between temperature and kinetic energy for an ideal gas?

Accepted Answer

The average kinetic energy of gas molecules is directly proportional to the absolute temperature.

Question 7

Which of the following compounds has the highest boiling point?

Accepted Answer

$\mathrm{H_2O}$

Question 8

A $2.00\ \mathrm{g}$ sample of a compound contains $0.040\ \mathrm{mol}$ of the compound. What is its molar mass?

Accepted Answer

$50.0\ \mathrm{g\cdot mol^{-1}}$

Question 9

Which of the following is the correct Lewis structure for $\mathrm{NH_3}$?

Accepted Answer

A nitrogen atom with three single bonds to hydrogen atoms and one lone pair on nitrogen.

Question 10

Which of the following best explains why ionic compounds tend to have higher melting points than covalent compounds?

Accepted Answer

Ionic compounds have strong electrostatic attractions between oppositely charged ions, requiring more energy to break.

Question 11

A $5.00\ \mathrm{g}$ sample of a hydrate of $\mathrm{CuSO_4}$ is heated, and $3.20\ \mathrm{g}$ of anhydrous $\mathrm{CuSO_4}$ remains. What is the percent by mass of water in the hydrate?

Accepted Answer

$36.0\%$

Question 12

Which of the following molecules has a trigonal planar electron geometry?

Accepted Answer

$\mathrm{BF_3}$

Question 13

Which of the following statements about the ideal gas law is correct?

Accepted Answer

It assumes that gas particles do not attract or repel each other and occupy no volume.

Question 14

Which of the following is the correct empirical formula for a compound containing $40.0\%$ carbon, $6.7\%$ hydrogen, and $53.3\%$ oxygen by mass?

Accepted Answer

$\mathrm{CH_2O}$

Question 15

Which of the following best describes the effect of increasing the molar mass of a gas on its rate of effusion?

Accepted Answer

The rate of effusion decreases as the molar mass increases.

Question 16

Which of the following molecules is expected to have the strongest London dispersion forces?

Accepted Answer

$\mathrm{I_2}$

Question 17

A $0.500\ \mathrm{mol}$ sample of $\mathrm{O_2}$ gas is at $25.0^\circ\mathrm{C}$ and $1.00\ \mathrm{atm}$. What is the volume of the gas? ($R = 0.0821\ \mathrm{L\cdot atm\cdot mol^{-1}\cdot K^{-1}}$)

Accepted Answer

$12.2\ \mathrm{L}$

Question 18

Which of the following best explains why $\mathrm{NH_3}$ is a polar molecule?

Accepted Answer

It has a trigonal pyramidal shape with a lone pair on nitrogen, resulting in a net dipole moment.

Question 19

Which of the following is the correct order of increasing strength of intermolecular forces?

Accepted Answer

London dispersion < dipole-dipole < hydrogen bonding

Question 20

A $1.00\ \mathrm{L}$ flask contains $0.0821\ \mathrm{mol}$ of an ideal gas at $273\ \mathrm{K}$. What is the pressure in the flask? ($R = 0.0821\ \mathrm{L\cdot atm\cdot mol^{-1}\cdot K^{-1}}$)

Accepted Answer

$1.00\ \mathrm{atm}$

General Chemistry Exam 2 Study Guide: Chapters 5, 6, and 8

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