chapter 19 worksheets 2013.docx

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Chapter 19 Worksheets

Bellwork:

Worksheet #1

1. Use the graph to answer the following questions.

a. Does the graph represent an endothermic or exothermic reaction?

b. Determine the ΔH for this reaction.

c. Determine the activation energy for this reaction.

d. What is the energy of the activated complex for this reaction?

2. How do catalysts speed up a reaction?

3. What are the four factors that affect reaction rates? How?

4. The following data were obtained at 55⁰C. (CH3)3CBr + OH- _{↔ (CH3)3COH + Br}

-a. Find the rate law:

Bellwork:

Worksheet 2

1. The following data were collected for the reaction: S2O8-2 _{+ 2 I}-

→

b. Find the specific rate constant, k:

c. What is the overall order of the reaction?

2. How can you determine whether a reaction is going to favor products or reactants being produced? 3. What is a rate limiting step in a reaction?

Experiment [(CH3)3CBr] [OH-] Initial rate (mol/L.s)

1 0.10 0.10 1.0 x 10-3

2 0.20 0.10 2.0 x 10-3

3 0.10 0.20 8.0 x 10-3

Experiment [S2O8-2_{] [I}-_{] Rate (mol/L}._s)

1 0.03 0.02 1.00

2 0.03 0.04 2.00

4. A 1L mixture at equilibrium at 827ºC contains 0.552 mol CO2, 0.552 mol H2, 0.448 mol CO, 0.448 mol H2O. What is the value of Keq? CO2(g) + H2(g) ↔ CO(g) + H2O(g)

a. Would more products or reactants be present at equilibrium? _______________

b. What types of substances are left out when calculating the equilibrium constant? __________________ 5. Please write the equilibrium expression for the following reactions:

a. 3 O2(g) ↔ 2 O3(g)

b. PCl5(g) ↔ PCl3(g) + Cl2(g)

c. N2(g) + 3 H2(g) ↔ 2 NH3(g)

d. 4H2(g) + CS2(g) ↔ CH4(g) + 2H2S(g)

6. For the reaction: 2HI (g) ↔ H2 (g) + I2 (g) the equilibrium concentrations of these 3 gases are [H2] = 0.0091 M; [I2] = 0.00059 M; [HI] = 0.0173 M. What is Keq?

Bellwork:

Worksheet 3

N2(g) + 3H2(g)<==>2NH3(g) + energy

1. In the equation above, which direction will the equilibrium shift with the following: a. Add NH3: _____

b. Add nitrogen gas: _____

c. Decrease the pressure: _____ d. Addition of a catalyst: _____

2. Why does the addition of a catalyst not affect equilibrium?

N

+ O

+ energy <==> 2 NO

3. In the equation above, which direction will the equilibrium shift with the following: a. Temperature is decreased: _____

b. Addition of NO: _____

4. Given the equation representing a reaction at equilibrium: N2(g) + 3H2(g)

<==>

a. decreasing the concentration of H2(g) b. decreasing the pressure

c. increasing the concentration of N2(g) d. increasing the temperature

5. Given the system at equilibrium: 2POCl3(g) + energy <==> 2PCl3(g) + O2(g) Which changes occur when O2(g) is added to this system?

a. The equilibrium shifts to the right and the concentration of PCl3(g)increases. b. The equilibrium shifts to the right and the concentration of PCl3(g)decreases. c. The equilibrium shifts to the left and the concentration of PCl3(g) increases. d. The equilibrium shifts to the left and the concentration of PCl3(g) decreases.

Bellwork:

Bellwork:

Worksheet 4

1. What is the equation to find Gibbs free energy? What is the difference between ΔS and ΔH?

2. What is the enthalpy of a free element in its standard state?

3. Determine the enthalpy of the following reactions using the ΔH values provided.

a. C (s) + O2 (g) ---> CO2 (g)

b. H2 (g) + O2 (g) --> H2O (l)

c. C (s) + 2 H2 (g) + ½ O2 (g) ---> CH3OH (l)

4. Predict the sign (+ or -) of the entropy change in each reaction.

a. CaCO3 (s)  CaO (s) + CO2 (g)

b. NH3 (g) + HCl (g)  NH4Cl (s)

c. 2NaHCO3 (s)  Na2CO3 (s) + H2O (g) + CO2 (s)

d. CaO (s) + CO2 (s)  CaCO3 (s)

Substance ΔH values (kJ/mol)

C (s) 1.88

O2 (g) 0.00

CO2 (g) -393.5

H2 (g) 0.00

H2O (l) -285.8

5. Given the following factors, will they give a spontaneous reaction?

a. +ΔH, -ΔS

b. –ΔH, +ΔS

c. –ΔH, -ΔS

d. +ΔH, +ΔS

6. 2NO + Cl2  2NOCl

Trial# [NO] [Cl2] Rate mol/L._min

1 0.10 0.10 0.18

2 0.10 0.20 0.36

3 0.20 0.20 1.44

a. What is the rate law?

b. What is the value for the rate constant, k?

c. What is the order of the reaction for NO and Cl2? What is the overall order of reaction?

d. What is the initial rate if the concentration of NO is 0.2M and Cl2 is 0.04M (use rate law and value of k to solve)?

Chapter 19 Review

1. For the reaction NO2 + O2 → 2N2O4 , the data shown was collected.

a. Write the rate law expression for the reaction.

b. Calculate the value of the rate constant.

c. Use the rate law expression and calculated

value of k to compute the initial rate of formation of N2O4, if the initial concentrations of NO2 and O2 were each 0.030M.

2. An energy diagram is shown to the right. Answer the following.

a. What is the definition of “activated complex”?

b. What is the definition of “activation energy”?

c. What is the potential energy of the products? ________

d. What is the potential energy of the reactants? ________

e. What is the activation energy of the forward reaction? ________

f. What is the activation energy of the reverse reaction? ________

g. What is ∆H for the forward reaction? ______

h. Draw a line to represent the reaction with a catalyst. What does the catalyst do to the rate of the reaction?

3. The rate law for the reaction NO(g) + O3(g) → NO2(g) + O2(g) is a first-order in NO and O3, and second order overall. Write the complete rate law for this reaction. ____________________________________________

4. Consider the decomposition of N2O5 in carbon tetrachloride (CCl4) at 45ºC. 2N2O5 (aq) ↔ 4NO2(g) + O2(g)

The reaction is first-order in N2O5, with the specific rate constant 6.08 x 10-4_{/s. Calculate the reaction rate at these} conditions.

a. [N2O5] = 0.200 mol/L b. [N2O5] = 0.319 mol/L

5. For the reaction A + B ↔ C, the activation energy of the forward reaction is 5 kJ and the total energy change is -20 kJ. What is the activation energy of the reverse reaction? (hint: draw a picture)

6. For the following reaction: Zn(s) + 2H+_{(aq) --> Zn}2+_{(aq) + H2(g) The reaction is exothermic.} Indicate the direction of the equilibrium shift.

a. add H+ _{________}

b. remove Zn2+ _{________}

c. decrease temp ________

d. decrease pressure ________ Trial # Initial [NO2] Initial [O2] Initial Rate of

e. add Zn (s) ________ f. add catalyst ________

6. A mixture at equilibrium at 827ºC contains 0.552 mol CO2, 0.552 mol H2, 0.448 mol CO, 0.448 mol H2O. What is the value of Keq? (ans: 0.659) CO2(g) + H2(g) ↔ CO(g) + H2O(g)

a. Would more products or reactants be present at equilibrium? _______________

7. List 2 ways that reaction rates can generally be increased:

a.) __________________ b.) ___________________ c.) ________________________

8. A catalyst __________________ reaction rates by ___________________ the activation energy. Biological catalysts are called ___________________.

9. It has been determined that the rate law for the following reaction is third-order overall and first-order with respect to HgCl2. Write the rate law for this reaction: 2HgCl2 + Na2C2O4  2NaCl + 2CO2 + Hg2Cl2

10. Write the equilibrium constant expression for the following reaction: 2N2O3(g)  4NO2(g) + O2(g)

a. Calculate Keq for the reaction if the equilibrium concentrations are [N2O5] = 0.50 M, [NO2] = 0.80 M, and [O2] = 0.20 M.

11. For the following reaction, calculate which direction the reaction will shift when these stresses are applied: 2NO2(g)  N2O4(g) + 57.2 kJ

a. The temperature is increased _______

b. The pressure is lowered ____________

c. NO2 is added ___________

d. N2O4 is added __________

12. Is entropy (disorder) increasing or decreasing in these reactions or processes?

a. 2XeO3(s)  2Xe(g) + 3O2(g)

b. NaCl(s)  Na+_{(aq) + Cl}-_(aq)

c. Loose stamps  Stamps in an album

d. Messy room  clean room

e. Ice  water

13. Which combination of factors will always give a spontaneous reaction?

a. +ΔH, -ΔS b. –ΔH, +ΔS c. –ΔH, -ΔS d. +ΔH, -ΔS