Q: The decomposition of $$\mathrm{SO_2Cl_2} is $$first order with a rate constant $$k = 2.0 \times 10$$^{-3}$$\ \mathrm{s}^{-1}. $$What is the half-life of the reaction?

$$t_{1/2} = \frac{0.693}{2.0 \times 10$$^{-3}$$} = 346.5\ \mathrm{s}$$

Q: For the reaction $$2H_2 (g) + CO (g) \rightleftharpoons CH_3OH (g)$$, $$K_c = 1.6 \times 10^2$ at equilibrium. If there are 17.1$$ \times $$10^{-2}$$ moles of H$$_2$$ and $$3.46 \times 10$$^{-3}$$ moles of CO in a 50.0$ L flask, how many moles of CH_3$OH are present at equilibrium?

$$1.19 \times 10$$^{-3}$$ moles

Question 1

For the reaction $$\mathrm{N_2$ (g) + 3H_2 (g) \rightarrow 2NH_3 (g)}$$, if the rate of disappearance of $$\mathrm{H_2$} is$$ $$0.084\ \mathrm{M/s}$$, what is the rate of formation of $$\mathrm{NH_3$}$$?

Accepted Answer

$$0.056\ \mathrm{M/s}$$

Question 2

Given the rate law for the reaction $$2NO (g) + Cl_2$ (g) ightarrow 2NOCl (g) is$$ $$	ext{rate} = k[NO]^2[Cl_2$]$$, what is the overall order of the reaction?

Accepted Answer

Third order

Question 3

For the reaction $$A (aq) + 2B (aq) ightarrow C (aq)$$, the rate law is $$	ext{rate} = k[A][B]^2. If$$ $$[A] is $$doubled and $$[B] is $$tripled, by what factor does the rate increase?

Accepted Answer

18

Question 4

The decomposition of $$\mathrm{SO_2Cl_2} is $$first order with a rate constant $$k = 2.0 	imes 10$$^{-3}$$\ \mathrm{s}^{-1}. $$What is the half-life of the reaction?

Accepted Answer

$$t_{1/2} = \frac{0.693}{2.0 	imes 10$$^{-3}$$} = 346.5\ \mathrm{s}$$

Question 5

A reaction has a rate constant of $$0.00122\ \mathrm{s}^{-1} at$$ $$27\ ^\circ\mathrm{C}$$ and $$0.228\ \mathrm{s}^{-1} at$$ $$77\ ^\circ\mathrm{C}. $$What is the activation energy ($$E_a) $$for the reaction? Use $$R = 8.314\ \mathrm{J\ $$mol^{-1}$$\ K$$^{-1}$$}.$$

Accepted Answer

$$E_a = 98.2\ \mathrm{kJ\ $$mol^{-1}$$}$$

Question 6

For the equilibrium $$2NOBr (g) ightleftharpoons 2NO (g) + Br_2$ (g)$$, if $$K_c = 3.07 	imes 10$$^{-4}$$ at 24$$^\circ\mathrm{C}$$, what is the expression for K_c$?

Accepted Answer

$$K_c = \frac{[NO]^2[Br_2$]}{[NOBr]^2}$$

Question 7

If a 4.00 L vessel contains $$0.0148$$ mol of NOBr, $$0.0126$$ mol of NO, and $$0.0085$$ mol of Br$$_2 at $$equilibrium, what is the value of $$K_c$$ for $$2NOBr (g) \rightleftharpoons 2NO (g) + Br_2$ (g)$$?

Accepted Answer

$$K_c = 0.160$$

Question 8

For the reaction $$2H_2 (g) + CO (g) ightleftharpoons CH_3OH (g)$$, $$K_c = 1.6 	imes 10^2$ at equilibrium. If there are 17.1$$ 	imes $$10^{-2}$$ moles of H$$_2$$ and $$3.46 	imes 10$$^{-3}$$ moles of CO in a 50.0$ L flask, how many moles of CH_3$OH are present at equilibrium?

Accepted Answer

$$1.19 	imes 10$$^{-3}$$ moles

Question 9

Anthropologists find a bone containing $$15.9\% of $$the original carbon-14. If the half-life of carbon-14 is $$5730$$ years, how old is the bone?

Accepted Answer

$$15,000$$ years

Question 10

For the reaction $$2SiOBr_2 (g) \rightleftharpoons $$SiO_2$$ (g) + $$SiBr_4$$ (g)$$, $$K = 0.038. $$Which of the following is the correct equilibrium expression?

Accepted Answer

$$K = \frac{[$$SiO_2$$][$$SiBr_4$$]}{[$$SiOBr_2$$]^2}$$

Question 11

For the endothermic reaction $$N_2 (g) + 3H_2 (g$$) \rightleftharpoons 2NH_3 (g)$$, which change will shift the equilibrium to the right?

Accepted Answer

Increase temperature

Question 12

Which of the following is the correct conjugate base of H$$_2S$$?

Accepted Answer

HS$$^-$$

Question 13

Which of the following acids is a strong acid?

Accepted Answer

HCl

Question 14

According to the Arrhenius definition, which of the following is classified as a base?

Accepted Answer

NaOH

Question 15

For the reaction $$2NO (g) + Cl_2$ (g) ightarrow 2NOCl (g)$$, which of the following mechanisms is consistent with the observed rate law $$	ext{rate} = k[NO]^2[Cl_2$]$$?

Accepted Answer

A slow step involving two NO molecules and one Cl$$_2$$ molecule

Question 16

If the initial concentration of $$\mathrm{SO_2Cl_2} is$$ $$1.00\ \mathrm{M}$$, how long will it take for the concentration to decrease to $$0.25\ \mathrm{M}$$? ($$k = 2.0 	imes 10$$^{-3}$$\ \mathrm{s}^{-1}$$, first order)

Accepted Answer

$$693\ \mathrm{s}$$

Question 17

Which of the following statements about the rate constant $$k is $$true?

Accepted Answer

It increases with temperature for most reactions.

Question 18

Which of the following is the correct equilibrium constant expression for the reaction $$4IBr (g) \rightleftharpoons 2I_2 (g) + 2Br_2 (g)$$?

Accepted Answer

$$K_c = \frac{[I_2$]^2[Br_2$]^2}{[IBr]^4}$$

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