Q: Which of the following is the correct rate law for the reaction $2\mathrm{NO}_2 \rightarrow 2\mathrm{NO} + \mathrm{O}_2$ if it is second order overall and first order in $\mathrm{NO}_2$?

$\text{Rate} = k[\mathrm{NO}_2]^2$

Q: Given the reaction $\mathrm{NO}(g) + \mathrm{O}_3(g) \rightarrow \mathrm{NO}_2(g) + \mathrm{O}_2(g)$ and the following data: Trial 1: $[\mathrm{NO}] = 1.00 \times 10^{-6}\ \mathrm{M}$, $[\mathrm{O}_3] = 3.00 \times 10^{-6}\ \mathrm{M}$, Rate $= 6.60 \times 10^{-5}\ \mathrm{M/s}$ Trial 2: $[\mathrm{NO}] = 1.00 \times 10^{-6}\ \mathrm{M}$, $[\mathrm{O}_3] = 6.00 \times 10^{-6}\ \mathrm{M}$, Rate $= 1.32 \times 10^{-4}\ \mathrm{M/s}$ Trial 4: $[\mathrm{NO}] = 2.00 \times 10^{-6}\ \mathrm{M}$, $[\mathrm{O}_3] = 9.00 \times 10^{-6}\ \mathrm{M}$, Rate $= 3.96 \times 10^{-4}\ \mathrm{M/s}$ What is the rate law for this reaction?

$\text{Rate} = k[\mathrm{NO}][\mathrm{O}_3]$

Question 1

A student wants to prepare 5.00 L of a 0.250 M NaOH solution. What mass of NaOH (molar mass = 40.0 g/mol) is required?

Accepted Answer

$50.0\ \mathrm{g}$

Question 2

Which of the following best describes a strong electrolyte?

Accepted Answer

A substance that completely dissociates into ions in solution.

Question 3

Which compound is water-insoluble according to solubility rules?

Accepted Answer

CaCO3

Question 4

A solution is made by dissolving 3.0 g of KF (molar mass = 58.1 g/mol) in 25.0 mL of water (density = 0.975 g/mL). What is the molality of the solution?

Accepted Answer

$2.06\ \mathrm{mol/kg}$

Question 5

Which of the following is the correct rate law for the reaction $2\mathrm{NO}_2 \rightarrow 2\mathrm{NO} + \mathrm{O}_2$ if it is second order overall and first order in $\mathrm{NO}_2$?

Accepted Answer

$	ext{Rate} = k[\mathrm{NO}_2]^2$

Question 6

Given the reaction $\mathrm{NO}(g) + \mathrm{O}_3(g) ightarrow \mathrm{NO}_2(g) + \mathrm{O}_2(g)$ and the following data:

Trial 1: $[\mathrm{NO}] = 1.00 	imes 10^{-6}\ \mathrm{M}$, $[\mathrm{O}_3] = 3.00 	imes 10^{-6}\ \mathrm{M}$, Rate $= 6.60 	imes 10^{-5}\ \mathrm{M/s}$
Trial 2: $[\mathrm{NO}] = 1.00 	imes 10^{-6}\ \mathrm{M}$, $[\mathrm{O}_3] = 6.00 	imes 10^{-6}\ \mathrm{M}$, Rate $= 1.32 	imes 10^{-4}\ \mathrm{M/s}$
Trial 4: $[\mathrm{NO}] = 2.00 	imes 10^{-6}\ \mathrm{M}$, $[\mathrm{O}_3] = 9.00 	imes 10^{-6}\ \mathrm{M}$, Rate $= 3.96 	imes 10^{-4}\ \mathrm{M/s}$

What is the rate law for this reaction?

Accepted Answer

$	ext{Rate} = k[\mathrm{NO}][\mathrm{O}_3]$

Question 7

Which of the following statements about the van’t Hoff factor ($i$) is correct?

Accepted Answer

It represents the number of ions produced per formula unit of solute.

Question 8

A solution is prepared by dissolving 2.50 moles of $\mathrm{H}_2\mathrm{SO}_4$ in 200 mL of water. What is the theoretical van’t Hoff factor ($i$) for $\mathrm{H}_2\mathrm{SO}_4$?

Accepted Answer

$i = 3$

Question 9

Which of the following will increase the rate of a chemical reaction according to Collision Theory?

Accepted Answer

Adding a catalyst

Question 10

A reaction has a rate law $	ext{Rate} = k[A]^2[B]$. If the concentration of $A$ is doubled and $B$ is tripled, by what factor does the rate increase?

Accepted Answer

12

Question 11

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

It decreases the activation energy and increases the reaction rate.

Question 12

For a first-order reaction, which of the following plots yields a straight line?

Accepted Answer

$\ln[A]$ vs. time

Question 13

A solution is made by dissolving 25.0 g of ethanol (molar mass = 46.1 g/mol) in 75.0 mL of water (density = 0.985 g/mL). If the freezing point depression is $-0.75\ ^\circ\mathrm{C}$ and $K_f$ for water is $1.86\ ^\circ\mathrm{C}/\mathrm{m}$, what is the molality of the solution?

Accepted Answer

$0.403\ \mathrm{mol/kg}$

Question 14

Given the following multi-step reaction:
1) $\mathrm{NO}_2 + \mathrm{NO}_2 \rightarrow \mathrm{NO}_3 + \mathrm{NO}$
2) $\mathrm{NO}_3 + \mathrm{CO} \rightarrow \mathrm{NO}_2 + \mathrm{CO}_2$
What is the overall balanced reaction and the intermediate?

Accepted Answer

Overall: $2\mathrm{NO}_2 + \mathrm{CO} \rightarrow \mathrm{NO} + \mathrm{CO}_2 + \mathrm{NO}_2$; Intermediate: $\mathrm{NO}_3$

Question 15

For the reaction $\mathrm{N}_2(g) + 3\mathrm{H}_2(g) \rightarrow 2\mathrm{NH}_3(g)$, if the rate of formation of $\mathrm{NH}_3$ is $2.0\ \mathrm{mol}/(\mathrm{L}\cdot\mathrm{s})$, what is the rate of consumption of $\mathrm{H}_2$?

Accepted Answer

$3.0\ \mathrm{mol}/(\mathrm{L}\cdot\mathrm{s})$

Question 16

Which of the following is NOT a colligative property?

Accepted Answer

Molar mass

Question 17

A solution of an unknown salt in water has a freezing point depression of $0.1395\ ^\circ\mathrm{C}$ at a concentration of $0.015\ \mathrm{m}$ ($K_f = 1.86\ ^\circ\mathrm{C}/\mathrm{m}$). If the cation is $\mathrm{Al}^{3+}$, which of the following could be the anion?

Accepted Answer

$\mathrm{PO}_4^{3-}$

Question 18

Which of the following statements about reaction order is correct?

Accepted Answer

The reaction order is the sum of the exponents in the rate law.

Question 19

Which of the following is a correct unit for the rate constant $k$ for a second-order reaction?

Accepted Answer

$\mathrm{M}^{-1}\mathrm{s}^{-1}$

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