Q: A solution is prepared by dissolving 0.5 mol of NaCl in 1.0 kg of water. What is the expected freezing point depression? ($K_f$ for water = $1.86\ \mathrm{^ ext{o}C\ kg\ mol^{-1}}$)

$\Delta T_f = 1.86\ \mathrm{^ ext{o}C} \times 1.0 \times 2 = 1.86\ \mathrm{^ ext{o}C}$

Q: Which of the following is the correct formula for calculating molarity ($M$)?

$M = \dfrac{\text{moles of solute}}{\text{volume of solution in liters}}$

Question 1

Which of the following best explains why adding a nonvolatile solute to water lowers its vapor pressure?

Accepted Answer

The solute particles occupy surface sites, reducing the number of water molecules able to escape into the vapor phase.

Question 2

A solution is prepared by dissolving 0.5 mol of NaCl in 1.0 kg of water. What is the expected freezing point depression? ($K_f$ for water = $1.86\ \mathrm{^	ext{o}C\ kg\ mol^{-1}}$)

Accepted Answer

$\Delta T_f = 1.86\ \mathrm{^	ext{o}C} 	imes 1.0 	imes 2 = 1.86\ \mathrm{^	ext{o}C}$

Question 3

Which of the following is the correct formula for calculating molarity ($M$)?

Accepted Answer

$M = \dfrac{	ext{moles of solute}}{	ext{volume of solution in liters}}$

Question 4

Which intermolecular force is primarily responsible for the high solubility of NaCl in water?

Accepted Answer

Ion-dipole interactions

Question 5

A reaction has the following rate law: $	ext{Rate} = k[A]^2[B]$. What is the overall order of the reaction?

Accepted Answer

Third order

Question 6

Which of the following factors will NOT increase the rate of a chemical reaction?

Accepted Answer

Decreasing the surface area of a solid reactant

Question 7

Given the following data for a reaction: doubling $[A]$ doubles the rate, doubling $[B]$ quadruples the rate. What is the rate law?

Accepted Answer

$	ext{Rate} = k[A][B]^2$

Question 8

Which statement best describes a catalyst in a chemical reaction?

Accepted Answer

It provides an alternative pathway with lower activation energy.

Question 9

A student mixes 0.1 mol of glucose ($C_6H_{12}O_6$) in 500 mL of water. What is the molarity of the solution?

Accepted Answer

$0.2\ \mathrm{M}$

Question 10

Which of the following best describes the role of intermediates in a reaction mechanism?

Accepted Answer

They are formed and consumed during the reaction, and do not appear in the overall equation.

Question 11

A reaction progress diagram shows a small peak followed by a larger peak before products are formed. What does the small peak represent?

Accepted Answer

The formation of an intermediate

Question 12

Which equation correctly relates the rate constant $k$ to the activation energy $E_a$ and temperature $T$?

Accepted Answer

$k = A e^{-E_a/RT}$

Question 13

Which of the following is NOT a colligative property?

Accepted Answer

Density

Question 14

A solution of KBr in water conducts electricity. Which statement best explains this observation?

Accepted Answer

KBr dissociates into ions that move freely in solution.

Question 15

Which graph would you use to determine the order of a reaction with respect to a reactant?

Accepted Answer

A plot of rate vs. concentration

Question 16

A reaction is zero order in $A$ and first order in $B$. Which rate law is correct?

Accepted Answer

$	ext{Rate} = k[B]$

Question 17

Which of the following would increase the boiling point of water the most?

Accepted Answer

Adding 1 mol of NaCl

Question 18

Which statement about solubility is correct?

Accepted Answer

Ionic solutes are most soluble in polar solvents due to ion-dipole interactions.

Question 19

Which of the following is true about the rate constant $k$ for a first-order reaction?

Accepted Answer

$k$ has units of $\mathrm{s^{-1}}$

General Chemistry Study Notes: Solutions and Kinetics

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