Q: Given a 40% (m/m) ethanol-water solution with a density of 0.931 g/mL at 25°C, what is the molarity of ethanol if you assume 100 g solution?

$M = \frac{0.868\,\text{mol}}{0.107\,\text{L}} = 8.11\,\text{M}$

Q: What is the mole fraction of ethanol in a 40% (m/m) ethanol-water solution, assuming 100 g solution?

$X_{\text{ethanol}} = \frac{0.868}{0.868 + 3.33} = 0.207$

Q: If 12.1 g urea is added to 50 mL acetone (density 0.785 g/mL), what is the mole fraction of acetone in the solution?

$X_{\text{acetone}} = \frac{0.676}{0.876} = 0.772$

Q: According to Henry's Law, which gas will have the highest solubility in water at 1 atm?

CO$_2$ ($k_H = 3.4 \times 10^{-2}$ M/atm)

Question 1

Which state of matter has the strongest intermolecular forces relative to thermal energy?

Accepted Answer

Solid

Question 2

A solution forms when the solvent-solute interactions are:

Accepted Answer

Stronger than both solvent-solvent and solute-solute interactions

Question 3

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

Accepted Answer

Dispersion (London) forces

Question 4

Given a 40% (m/m) ethanol-water solution with a density of 0.931 g/mL at 25°C, what is the molarity of ethanol if you assume 100 g solution?

Accepted Answer

$M = \frac{0.868\,	ext{mol}}{0.107\,	ext{L}} = 8.11\,	ext{M}$

Question 5

Which of the following best explains why gases are compressible, but solids and liquids are not?

Accepted Answer

Gas molecules are far apart, while solid and liquid molecules are close together

Question 6

What is the mole fraction of ethanol in a 40% (m/m) ethanol-water solution, assuming 100 g solution?

Accepted Answer

$X_{	ext{ethanol}} = \frac{0.868}{0.868 + 3.33} = 0.207$

Question 7

Which liquid in the table has the highest enthalpy of vaporization at its boiling point?

Accepted Answer

Water

Question 8

If 12.1 g urea is added to 50 mL acetone (density 0.785 g/mL), what is the mole fraction of acetone in the solution?

Accepted Answer

$X_{	ext{acetone}} = \frac{0.676}{0.876} = 0.772$

Question 9

According to Henry's Law, which gas will have the highest solubility in water at 1 atm?

Accepted Answer

CO$_2$ ($k_H = 3.4 	imes 10^{-2}$ M/atm)

Question 10

Which scenario will most likely result in a solution forming, based on Table 14.2?

Accepted Answer

Solvent-solute interactions are equal to solvent-solvent and solute-solute interactions

Question 11

What is the freezing point depression ($\Delta T_f$) for a solution made by dissolving 25 g CaCl$_2$ (MM = 110.98 g/mol) in 100 g water ($K_f = -1.86$ °C/m)?

Accepted Answer

$\Delta T_f = -4.19$ °C

Question 12

Which property is NOT a colligative property?

Accepted Answer

Enthalpy of solution

Question 13

If a cell is placed in a hypertonic solution, what will happen?

Accepted Answer

Water will flow out of the cell

Question 14

What is the osmotic pressure ($\pi$) of a solution containing 5.00 M urea at 313 K? ($R = 0.08206$ L·atm/mol·K)

Accepted Answer

$\pi = (5.00)(0.08206)(313) = 128$ atm

Question 15

Which of the following best describes the dynamic equilibrium in a saturated NaCl solution?

Accepted Answer

NaCl dissolves and crystallizes at equal rates

Question 16

If the concentration of $[BrO_3^-]$ is doubled in the reaction $BrO_3^- + Br^- + 6H^+ \rightarrow 3Br_2 + 3H_2O$, what happens to the rate if the reaction is first order in $BrO_3^-$?

Accepted Answer

The rate doubles

Question 17

Which of the following is true about the rate law for a reaction $aA + bB \rightarrow cC + dD$?

Accepted Answer

The exponents in the rate law are determined experimentally

Question 18

For the reaction $H_2(g) + I_2(g) \rightarrow 2HI(g)$, if $\Delta[H_2]/\Delta t = -0.0165$ M/s, what is $\Delta[HI]/\Delta t$?

Accepted Answer

$\Delta[HI]/\Delta t = 2 	imes 0.0165 = 0.033$ M/s

Liquids, Solids, Intermolecular Forces, Solutions, and Chemical Kinetics: Mini-Study Guide

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