Question 1

Which of the following best explains why the boiling point of water is higher than that of methane ($$\mathrm{CH_4$}$$), even though both are small molecules?

Accepted Answer

Water molecules form strong hydrogen bonds, which require more energy to break.

Question 2

A student is asked to calculate the enthalpy change for the reaction: $$\mathrm{2H_2(g) + O_2$(g) \rightarrow 2H_2O(l)}. $$Given the following bond enthalpies: $$\mathrm{H-H}$$: $$436\ \mathrm{kJ/mol}$$, $$\mathrm{O=O}$$: $$498\ \mathrm{kJ/mol}$$, $$\mathrm{O-H}$$: $$463\ \mathrm{kJ/mol}$$, what is the enthalpy change for the reaction?

Accepted Answer

$$-484\ \mathrm{kJ}$$

Question 3

Which statement correctly describes the geometry of $$\mathrm{NH_3$}$$ according to VSEPR theory?

Accepted Answer

$$\mathrm{NH_3$}$$ has a trigonal pyramidal geometry due to one lone pair on nitrogen.

Question 4

Which of the following molecules is polar?

Accepted Answer

$$\mathrm{$$CHCl_3$$}$$

Question 5

A solution is prepared by dissolving $$10.0\ \mathrm{g} of$$ $$\mathrm{NaCl} in$$ $$100.0\ \mathrm{g} of $$water. What is the mole fraction of $$\mathrm{NaCl} in $$the solution? ($$\mathrm{M_{NaCl}} = 58.44\ \mathrm{g/mol}$$, $$\mathrm{M_{H_2O}} = 18.02\ \mathrm{g/mol})$$

Accepted Answer

$$0.030$$

Question 6

Which of the following best describes the effect of adding a nonvolatile solute to a solvent?

Accepted Answer

The vapor pressure of the solvent decreases.

Question 7

Which equation is used to relate the vapor pressure of a liquid to temperature?

Accepted Answer

$$\ln P = -\dfrac{\Delta H_{vap}}{R} \left( \dfrac{1}{T} \right) + C$$

Question 8

A sample of water at $$100^\circ\mathrm{C} is $$exposed to atmospheric pressure. Which intermolecular force is primarily responsible for its relatively high boiling point?

Accepted Answer

Hydrogen bonding

Question 9

Which of the following statements about phase diagrams is correct?

Accepted Answer

The triple point is where solid, liquid, and gas phases coexist in equilibrium.

Question 10

A solution is made by mixing $$50.0\ \mathrm{g} of $$ethanol ($$\mathrm{C_2H_5OH}$$, $$M = 46.07\ \mathrm{g/mol}) $$and $$50.0\ \mathrm{g} of $$water ($$M = 18.02\ \mathrm{g/mol}). $$What is the mole fraction of ethanol in the solution?

Accepted Answer

$$0.164$$

Question 11

Which of the following is NOT a colligative property?

Accepted Answer

Density

Question 12

Which intermolecular force is present in all substances, regardless of polarity?

Accepted Answer

London dispersion forces

Question 13

A chemist wants to prepare $$250.0\ \mathrm{mL} of$$ $$0.100\ \mathrm{M}$$ $$\mathrm{NaCl}$$ solution. How many grams of $$\mathrm{NaCl}$$ are required? ($$M_{NaCl} = 58.44\ \mathrm{g/mol})$$

Accepted Answer

$$1.46\ \mathrm{g}$$

Question 14

Which of the following best describes the relationship between lattice energy and ionic radius?

Accepted Answer

Lattice energy increases as ionic radius decreases.

Question 15

Which of the following is the correct formula for calculating freezing point depression?

Accepted Answer

$$\Delta T_f = K_f m$$

Question 16

Which statement about hybridization is correct for the carbon atom in $$\mathrm{CO_2$}$$?

Accepted Answer

The carbon atom is $$sp$$ hybridized.

Question 17

A solution contains $$0.50\ \mathrm{mol} of $$glucose ($$\mathrm{C_6H_{12}O_6$}) $$dissolved in $$1.0\ \mathrm{kg} of $$water. What is the boiling point elevation if $$K_b$$ for water is $$0.512\ ^\circ\mathrm{C}/\mathrm{molal}$$?

Accepted Answer

$$0.256\ ^\circ\mathrm{C}$$

Question 18

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

Accepted Answer

Ionic bonds are stronger than covalent bonds due to electrostatic attraction between ions.

Question 19

Which of the following is the correct expression for Raoult's Law for a solution containing a nonvolatile solute?

Accepted Answer

$$P_{solution} = X_{solvent} P^\circ_{solvent}$$

Question 20

Which of the following factors will increase the rate of vaporization of a liquid?

Accepted Answer

Increasing the temperature of the liquid

General Chemistry II Exam III Review: Chemical Bonding, Intermolecular Forces, and Solutions

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