Q: Given the balanced equation: $$2NO(g) + Cl_2$(g) \rightarrow 2NOCl(g)$$, which expression correctly represents the rate of appearance of NOCl?

$$\text{Rate} = +\frac{1}{2} \frac{\Delta[NOCl]}{\Delta t}$$

Q: For the reaction $$2SO_2(g) + O_2$(g) \rightarrow 2SO_3(g)$$, experimental data shows that doubling $$[SO_2$]$$ doubles the rate, while doubling $$[O_2$]$$ quadruples the rate. What is the correct rate law for this reaction?

$$\text{Rate} = k[SO_2$][O_2$]^2$$

Q: Given the following proposed mechanism: Step 1 (fast): $$A + B \rightleftharpoons 2A$$ Step 2 (slow): $$2A \rightarrow 2AB ($$overall reaction: $$A + B \rightarrow 2AB) $$What is the correct rate law for the overall reaction?

$$\text{Rate} = k[A]^{1/2}[B]$$

Q: Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine. If it takes 142 seconds for the initial concentration of HI to decrease from $$6.75 \times 10$$^{-2}$$ M to 5.10$$ \times $$10^{-2} M$$, what is the rate constant for the reaction at this temperature?

$$9.69 \times 10$$^{-2}$$\ ext{M}^{-1}\text{s}^{-1}$$

Question 1

A compound is found to have a molar mass of 598 g/mol. If 35.8 mg of the compound is dissolved in enough water to make 175 mL of solution at 25°C, what is the osmotic pressure of the solution? (Use $$R = 0.08206 L$$·atm/mol·K and convert your answer to torr.)

Accepted Answer

36 torr

Question 2

A solution contains 5.0 grams of KCl and 550.0 grams of water. The freezing-point-depression constant ($$K_f) $$for water is 1.86°C/m. What is the freezing point of the solution? (Molar mass of KCl = 74.5513 g/mol, assume ideal behavior.)

Accepted Answer

$$-0.45^	ext{o}C$$

Question 3

Given the balanced equation: $$2NO(g) + Cl_2$(g) \rightarrow 2NOCl(g)$$, which expression correctly represents the rate of appearance of NOCl?

Accepted Answer

$$	ext{Rate} = +\frac{1}{2} \frac{\Delta[NOCl]}{\Delta t}$$

Question 4

For the reaction $$2SO_2(g) + O_2$(g) \rightarrow 2SO_3(g)$$, experimental data shows that doubling $$[SO_2$]$$ doubles the rate, while doubling $$[O_2$]$$ quadruples the rate. What is the correct rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[SO_2$][O_2$]^2$$

Question 5

Which of the following should be plotted to show that experimental concentration data fits a first-order reaction?

Accepted Answer

$$\ln[A] vs. $$time

Question 6

The rate constant for the first-order decomposition of $$N_2O_5 is$$ $$3.40\ 	ext{s}^{-1}. $$What is the half-life of the reaction?

Accepted Answer

$$0.204\ 	ext{s}$$

Question 7

For a second-order decomposition of HI with a rate constant $$k = 1.80 	imes 10$$^{-3}$$\ 	ext{M}^{-1}	ext{s}^{-1}$$, how much HI remains after 27.3 s if the initial concentration is 4.78 M?

Accepted Answer

3.87 M

Question 8

A first-order rearrangement of $$CH_3NC is $$measured to have a rate constant of $$3.61 	imes 10$$^{-15}$$\ 	ext{s}^{-1} at 298 K $$and $$8.66 	imes 10$$^{-7}$$\ 	ext{s}^{-1} at 425 K. $$What is the activation energy for this reaction?

Accepted Answer

$$160\ 	ext{kJ/mol}$$

Question 9

Given the following proposed mechanism:
Step 1 (fast): $$A + B \rightleftharpoons 2A$$
Step 2 (slow): $$2A \rightarrow 2AB ($$overall reaction: $$A + B \rightarrow 2AB)
$$What is the correct rate law for the overall reaction?

Accepted Answer

$$	ext{Rate} = k[A]^{1/2}[B]$$

Question 10

For the reaction $$X + 3Y ightarrow 2Z$$, the rate law is $$	ext{Rate} = k[X][Y]^2. $$What is the overall order of the reaction?

Accepted Answer

3

Question 11

Hydrogen iodide decomposes at 800 K via a second-order process to produce hydrogen and iodine. If it takes 142 seconds for the initial concentration of HI to decrease from $$6.75 	imes 10$$^{-2}$$ M to 5.10$$ 	imes $$10^{-2} M$$, what is the rate constant for the reaction at this temperature?

Accepted Answer

$$9.69 	imes 10$$^{-2}$$\ 	ext{M}^{-1}	ext{s}^{-1}$$

Question 12

Which of the following changes will shift the equilibrium of an exothermic reaction to the left?

Accepted Answer

Increasing temperature

Question 13

For the equilibrium $$N_2O_4(g) \rightleftharpoons 2NO_2(g)$$, which of the following will increase the amount of $$NO_2 at $$equilibrium?

Accepted Answer

Increasing the volume of the container

Question 14

Which statement about the equilibrium constant $$K is $$TRUE?

Accepted Answer

It is only affected by temperature.

Question 15

A solution is prepared by dissolving 0.50 mol of NaCl in 1.0 kg of water. What is the boiling point elevation of the solution? ($$K_b$$ for water = $$0.512^	ext{o}C/m$$, assume ideal behavior.)

Accepted Answer

$$1.02^	ext{o}C$$

Question 16

Which of the following statements is FALSE regarding chemical kinetics?

Accepted Answer

The rate law for a reaction can be determined from its balanced equation.

Question 17

A reaction has a rate constant $$k = 2.5 	imes 10$$^{-3}$$\ 	ext{s}^{-1} at 300 K $$and $$k = 1.0 	imes 10$$^{-2}$$\ 	ext{s}^{-1} at 350 K. $$What is the activation energy ($$E_a) $$for the reaction? ($$R = 8.314\ 	ext{J/mol·K})$$

Accepted Answer

$$27.6\ 	ext{kJ/mol}$$

Question 18

Which of the following is the correct expression for the equilibrium constant $$K_c$$ for the reaction $$2A(g) + B(g) \rightleftharpoons 3C(g)$$?

Accepted Answer

$$K_c = \frac{[C]^3}{[A]^2[B]}$$

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