AP Chemistry – Ch12,13 Homework
Ch12 HW#1 p602 23,24,25,26,27
23. 2NO(g) + Cl2(g)  2NOCl(g)
These results obtained:
Ch12 HW#2 1-3
1. The graph shows the decomposition
of hydrogen peroxide by the following equation:
2H2O2(l)  2H2O(l) + O2(g)
The slopes are found at 4M and 2M.
a. What is the order?
b. Write the generic rate law.
What is the rate law?
What is the rate constant?
24. 2I–(aq) + S2O8–2(aq)  I2(aq) + 2SO4–2(aq)
These results were obtained:
a) Determine the rate law
b) Rate constant
25. 2NOCl(g)  2NO(g) + Cl2(g)
These results obtained:
2. Use slope to determine the order of the reaction.
a) Determine the rate law b) Rate constant
26. I–(aq) + OCl–(aq)  OI–(aq) + Cl–(aq)
These results obtained:
3. Graph the data to determine the order of the
reaction.
a) Determine the rate law
b) Rate constant
27. Rate of rxn between hemoglobin and carbon
dioxide.
a. Determine the orders.
b. Rate law.
c. Rate constant.
d. Initial rate for
[Hb] = 3.36, [CO] = 2.40
Lab12.1 Pre-laboratory Questions
Ch12 HW#4 p605+ 49,50,51,54,55,56,57
1. What are some examples of reactions that people may
49. For the reaction, indicate
wish to speed up or slow down?
a. the positions of reactants and products
2. In each of the following three examples, explain how the
b. the activation energy
molecules differ in the two items described:
c. ∆E for the reaction
a. water at 70°C and water at 40°C.
b. 5 M glucose solution and 6 M glucose solution,
both at room temperature.
c. a 64cm3 cube of sugar and a 3cm x 8cm x 4cmcm
rectangular cube of sugar.
50. Draw a rough sketch of the energy profile for each
Ch12 HW#3 p605 45,46,47,48
of the following cases.
45. Write the rate laws for the following elementary
a. ∆E=+10kJ/mol, Ea= 25 kJ/mol
reactions.
b. ∆E=-10 kJ/mol, Ea= 50 kJ/mol
a. CH3NC(g)  CH3CN(g)
c. ∆E= -50 kJ/mol, Ea= 50 kJ/mol
b. O3(g) + NO(g) O2(g) + NO2
51. The activation energy for the reaction
46. Write the rate laws for the following elementary
NO2(g) +CO(g) → NO(g) +CO2(g)
reactions.
is 125 kJ/mol, and ∆E for the reaction is -216 kJ/mol.
a. O3(g)  O2(g) + O(g)
What is the activation energy for the reverse reaction?
b. O3(g) + O(g)  2O2(g)
[NO(g) + CO2(g) →NO2(g) + CO(g)]
47. A proposed mechanism for a reaction is
54. The reaction: (CH3)3CBr + OH- → (CH3)3COH + BrC4H9Br  C4H9+ + Br—
Slow
in a certain solvent is first order with respect
+
+
C4H9 + H2O  C4H9OH2
Fast
to (CH3)3CBr and zero order with respect to OH-.
+
+
C4H9OH2 + H2O  C4H9OH + H3O Fast
In several experiments, the rate constant k
Write the rate law expected for this mechanism.
was determined at different temperatures.
What is the overall balanced equation for the reaction?
A plot of ln(k) versus 1/T was constructed resulting
What are the intermediate in the proposed
in a straight line with a slope value of -1.1 x 104 K
mechanism?
and y-intercept of 33.5. Assume k has units of s-1.
48. The mechanism for the reaction of nitrogen dioxide
a) Determine the activation energy for this reaction.
with carbon monoxide to form nitric oxide
b) Determine the value of the frequency factor A.
and carbon dioxide is thought to be
c) Calculate the value of k at 25˚C.
NO2 + NO2  NO3 + NO
Slow
55. At 25˚C the first-order rate constant for a reaction
NO3 + CO  NO2 + CO2
Fast
is 2 x 103 s-1. The activation energy is 15 kJ/mol.
Write the rate law expected for this mechanism.
What is the value of the rate constant at 75˚C?
What is the overall balanced equation for the reaction? 56. A first-order reaction has rate constants of 4.6 x 10-2 s-1
and 8.1 x 10-2 s-1 at 0˚C and 20˚C respectively.
What is the value of the activation energy?
Ch12 HW#5 p604 53,57,58
53. Experimental values for the temperature dependence of the rate constant for the gas-phase reaction
NO + O3 → NO2 + O2 are as follows:
Make a graph of this
data, and determine the activation energy for this rxn.
57. A certain reaction has an activation energy of 54 kJ/mol. As the temperature is increased from 22˚C to a higher
temperature, the rate constant increases by a factor of 7. Calculate the higher temperature.
58. Chemists commonly use a rule of thumb that an increase in 10K in temp doubles the rate of the reaction.
What must the activation energy be for this statement to be true for a temp increase from 25°C to 35°C?
Ch12 HW#6 p606 59,60,62
59. One mechanism for the destruction of ozone in the upper atmosphere is:
O3(g) + NO(g)  NO2(g) + O2(g)
Slow
NO2(g) + O(g)  NO(g) + O2(g)
Fast
Overall Reaction: O3(g) + O(g)  2O2(g)
a) What species is a catalyst?
b) What species is an intermediate?
c) Ea for the uncatalyzed reaction is 14.0kJ. Ea for the catalyzed reaction is 11.9kJ. What is the ratio of the rate
constant for the catalyzed reaction to that for the uncatalyzed reaction at 25°C? Assume same freq factor, A.
60. One of the concerns about the use of Freons is that they will migrate to the upper atmosphere, where chlorine
atoms can be generated by the following reaction: CCl2F2  CF2Cl + Cl
Chlorine atoms can act as a catalyst for the destruction of ozone.
This activation energy for the reaction:
Cl + O3  ClO + O2 is 2.1 kJ/mol.
Which is the more effective catalyst for the destruction of ozone, Cl or NO? (Hint: NO from #59.)
62. The decomposition of NH3 to N2 and H2 was studied on two surfaces:
Without a catalyst, the activation energy is 335 kJ/mol.
a) Which surface is the better heterogeneous catalyst for the
decomposition of NH3? Why?
b) How many time faster is the reaction at 298 K on the W surface compared with the reaction with no catalyst
present? Assume that the frequency factor A is the same for each reaction.
NH 3 
Rate  k
c) The decomposition reaction of the two surfaces obeys a rate law of the form:
H 2 
How can you explain the inverse dependence of the rate on the H2 concentration?
Ch13 HW#1 p650 19,23,24,25,27
19. Write the equilibrium expression (K) for each of the following gas-phase reactions.
a. N2(g) + O2(g) → 2NO(g)
b. N2O4(g)↔2NO2(g)
c. SiH4(g) + 2Cl2(g)↔SiCl4(g) + 2H2(g)
d. 2PBr3(g) + 3Cl2(g)↔ 2PCl3(g) + 3Br2(g)
23. At high temperatures, elemental nitrogen and oxygen react with each other to form oxygen monoxide:
N2(g) + O2(g)↔2NO(g)
Suppose the system is analyzed at a particular temperature, and the equilibrium concentrations are found to be
[N2]=0.041M, [O2]=0.0078M, and [NO]=4.7 x 10-4M. Calculate the value of K for the reaction.
24. For the reaction:
N2(g) + 3Cl2(g)↔2NCl3(g)
an analysis of an equilibrium mixture is performed
at a certain temperature. It is found that [NCl3(g)] = 1.9 x 10-1M, [N2(g)] = 1.4 x10-3M, and [Cl2(g) ] = 4.3 x 10-4M.
Calculate K for the reaction at this temperature.
25. At a particular temperature, a 3.00-L flask contains 3.50 mol HI, 4.10 mol H2, and 0.30 mol I2 in equilibrium.
Calculate K at this temperature for the reaction:
H2(g) + I2(g)↔2HI(g)
27. The following equilibrium pressures at a certain temperature were observed for the reaction
2NO2(g) ↔ 2NO(g) + O2(g)
PNO2 = 0.55 atm PNO = 6.5 x 10-5 atm PO2 = 4.5 x 10-5 atm
Calculate the value for the equilibrium constant Kp at this temperature.
Ch13 HW#2 p651 29,31,33,37
29. At 25˚C, K = 3.7x109 for the reaction
CO(g)+Cl2(g)COCl2(g)
Calculate Kp at this temperature.
Hint: the relationship between K and Kp is: Kp = K(RT)∆n , where ∆n is the difference between the sum
of the coefficients of the gaseous products minus sum of the coefficients of the gaseous reactants.
(I don’t think this is important to remember, just be aware.)
31.Write expressions for K for the following reactions:
a. P4(s)+5O2(g)  P4O10(s)
b. NH4NO3(s)  N2O(g)+2H2O(g)
c. CO2(g)+NaOH(s)  NaHCO3(s)
d. S8(s)+8O2(g)  8SO2(g)
33. Consider the following reaction at a certain temperature: 4Fe(s)+3O2(g)  2Fe2O3(s)
An equilibrium mixture contains 1.0 mol Fe, 1.0х10-3 mol O2, and 2.0 mol Fe2O3 all in a 2.0-L container.
Calculate the value of K for this reaction.
37. The equilibrium constant, K, is 2.4х103 at a certain temperature for the reaction
2NO(g)  N2(g)+O2(g)
For which of the following sets of conditions is the system at equilibrium?
For those that are not at equilibrium, in which direction will the system shift?
a. A 1.0-L flask contains 0.024 mol NO, 2.0 mol N2, and 2.6 mol O2.
b. A 2.0-L flask contains 0.032 mol NO, 0.62 mol N2, and 4.0 mol O2.
c. A 3.0-L flask contains 0.060 mol NO, 2.4 mol N2, and 1.7 mol O2.
Ch13 HW#3 p652 41,43,45,47,49,55
41. The equilibrium constant, K, for the reaction:
H2(g) + F2(g) ↔ 2HF(g)
3
has the value 2.1 x 10 at a particular temperature. When the system is analyzed at equilibrium mixture at this
temperature, the concentrations of H2(g) and F2(g) are both found to be 0.0021 M.
What is the concentration of HF(g) in the equilibrium system under these conditions?
43. A 1.00-L flask was filled with 2.00 mol gaseous SO2 and 2.00 mol gaseous NO2 and heated. After the equilibrium
was reached, it was found that 1.30 mol gaseous NO was present.
Assume that the reaction SO2(g) + NO2(g) ↔ SO3(g) + NO(g)
occurs under these conditions. Calculate the value of the equilibrium constant, K, for this reaction.
45. At a particular temperature, 12.0 mol of SO3 is placed into a 3.0-L rigid container, and the SO3 dissociates
by the reaction
2SO3(g) ↔ 2SO2(g) + O2(g)
At equilibrium, 3.0 mol of SO2 is present. Calculate K for this reaction.
47. At a particular temperature, K= 3.75 for the reaction
SO2(g) + NO2 ↔ SO3(g) + NO(g)
If all four gases had initial concentrations of 0.800 M, calculate the equilibrium concentrations of the gases.
49. At 2200˚C, Kp = 0.050 for the reaction
N2(g) + O2(g) ↔ 2NO(g)
What is the partial pressure of NO in equilibrium with N2 and O2 that were placed in a flask at initial pressures
of 0.80 and 0.20 atm, respectively?
55. At a particular temperature, K =4.0 х 10-6 for the reaction
2CO2(g) ↔ 2CO(g) + O2(g)
If 2.0 mol CO2 is initially placed into a 5.0-L vessel, calculate the equilibrium concentrations of all species.
Ch13 HW#4 p653 59,61,63,65
59. Suppose that the reaction system
UO2(s) + 4HF(g) ↔ UF4(g) + 2H2O(g)
has already reached equilibrium. Predict the effect that each of the following changes has on equilibrium.
Tell whether the systems shifts to the left, right, or remains unaffected.
a. Additional UO2 is added.
b. The reaction is performed in a glass reaction vessel; HF attacks and reacts with the glass.
c. Water vapor is removed.
61. An important in the commercial production of hydrogen is
CO(g) + H2O(g) ↔ H2(g) + CO2(g)
How will this system at equilibrium shift in each of the following five cases?
a. Gaseous carbon dioxide is removed.
b. Water vapor is removed.
c. The pressure is increased by adding helium gas.
d. The temperature is increased (the reaction is exothermic).
e. Gaseous sulfur dioxide is removed.
63. In which direction will the position of the equilibrium
2HI(g) ↔ H2(g) + I2(g)
be shifted for each of the following changes?
a. H2 is added.
b. I2 is removed.
c. HI is removed.
d. Some Ar(g) is added.
e. The volume of the container is doubled. f. The temperature is decreased (the reaction is exothermic).
65. The reaction to prepare methanol from hydrogen and carbon monoxide
CO(g) + 2H2(g) ↔ CH3OH(g)
is exothermic. If you want to use this process to produce methanol commercially
would high or low temperatures favor a maximum yield?
Ch12 Rev p602 28,56,71 Ch13 p650 26,38,48,57,62
28. The following data were obtained for the reaction:
where
–
2CLO2(aq) + 2OH (aq) ↔ ClO3 (aq) + ClO2 (aq) + H2O(l)
a. Determine the rate law and the value of
the rate constant.
b. What would be the initial rate for an experiment
with
[CLO2]0 = 0.175 mol/L and [OH-]0 = 0.0844 mol/L?
56. A first order reaction has rate constants of 4.6x10-2 s-1
and 8.1x10-2 s-1 at 0˚C and 20˚C, respectively.
What is the value of the activation energy?
71. A study was made of the effect of the hydroxide
concentration on the rate of the reaction
I-(aq) + OCl-(aq) ↔ IO-(aq) + Cl-(aq)
the following data was obtained:
Ch13, #26. At a particular temperature, a 3.00L flask at equilibrium contains 2.80x10-4 mol N2, 2.50x10-5 mol O2,
and 2.00x10-2 mol N2O. Calculate k at this temperature for the reaction
2N2(g) + O2(g) ↔ 2N2O(g)
3
38. The equilibrium constant , kp, is 2.4 x 10 at a certain temperature for the reaction 2NO(g) ↔ N2(g) + O2(g)
For which of the following sets of conditions is the system at equilibrium?
For those that are not at equilibrium, in which direction will the system shift ?
a. PNO = 0.010 atm, PN2 = 0.11 atm, PO2 = 2.0atm
b. PNO =0.0078 ATM, PN2 = 0.36 atm,PO2 = 0.67atm
c. PNO = 0.0062 ATM, PN2 = 0.51 atm, PO2 = 0.18 atm
48. At a particular temperature , K = 1.00 x 102 for the reaction
H2(g) + I2(g) ↔ 2HI(g)
In an experiment 1.00 mol H2, 1.00 mol I2 and 1.00 mol HI are introduced into a 1.00 L container.
Calculate the concentration of all species when equilibrium is reached.
57. A sample of solid ammonium chloride was place in an evacuated container and then heated so that it decomposed
ammonium gas and hydrogen chloride gas. After heating the partial pressure of NH3 in the container was found
to be 2.2 atm. Calculate Kp at this temperature for the decomposition reaction.
NH4Cl(s) ↔ NH3(g) + HCl(g)
62. What will happen to the number of moles of SO3 in equilibrium with SO2 and O2 in the reaction
2 SO3(g)
2SO2(g) + O2(g)
∆H˚ = 197 kJ
in each of the following cases:
a. Oxygen gas is added
b. Pressure is increased by decreasing the volume of the container.
c. The pressure is increased by adding argon gas.
d. The temperature is decreased.
e. Gaseous sulfur dioxide is added.