1. Pure SO3 Is Introduced Into a Vessel at a Pressure of 4.0 Atm. a Reaction Occurs According
FALL 05 EXAM 1
F05 Ex1 #10
1. Pure SO3 is introduced into a vessel at a pressure of 4.0 atm. A reaction occurs according to the equation:
2 SO3(g) 2 SO2(g) + O2(g)
If at a particular temperature the partial pressure of SO3 is 1.4 atm at equilibrium, what is the numerical value of Keq?
F05 Ex 1 #11
2. ClO– is a stronger base than C2H3O2–, and CN– is a stronger base than ClO–. Place the following acids in order of decreasing strength: HClO, HC2H3O2, HCN (Place the strongest acid on the left, and the weakest acid on the right.)
______
F05 ex 1 #12
3. What is the pH of 0.025 M HNO3?
F05 Ex 1 #13
4. What is [H+] in 0.30 M Ca(OH)2?
F05 ex 1 #14
5. If Keq = 1.00 x102 for H2(g) + I2(g) 2 HI(g), what is Keq for HI(g) ½ H2(g) + ½ I2(g)?
F05 ex 1 #16
6. At a particular temperature, Keq = 9.0 x10–5 for the reaction:
H2O(g) + Cl2O(g) 2HOCl(g).
If pure H2O(g) and pure Cl2O(g) are introduced into a vessel at 2.0 atm and 3.0 atm respectively, what is the partial pressure of HOCl at equilibrium?
F05 ex 1 #17
7. At a particular temperature Keq = 45 for the reaction:
2 SO3(g) 2 SO2(g) + O2(g)
In a particular reaction vessel, the partial pressures are as follows: P(SO3) = 0.25 atm; P(SO2) = 4.0 atm; P(O2) = 0.30 atm
Is the system at equilibrium? Explain your answer.
If the system is not at equilibrium, what direction will it shift to reach equilibrium? Very briefly explain.
S06 Ex 1 #9
8. What is the pH of an aqueous solution of 0.005 M HClO4?
S06 ex 1 #10
9. If Keq= 1.00x103 for 2 NOBr (g) 2 NO (g) + Br2 (g) what is Keq for the following reaction: NO (g) + 1/2 Br2 (g) NOBr (g)?
S06 ex1 #11
10. At 900K, the equilibrium constant (Kp) for the following reaction is 0.345
2 SO2 (g) + O2 (g) 2 SO3 (g)
In a system already at equilibrium at 900K, the partial pressure of SO2 is 35.0 atm and the partial pressure of O2 is 15.9 atm. What is the partial pressure of SO3 in this system?
S06 ex1 #13
11. What is the pH of an aqueous solution containing 0.10 M NaOH?
S06 ex 1 #15
12. At a particular temperature, Keq = 80. for the reaction:
N2 (g) + 3 H2 (g) 2 NH3 (g)
At this particular temperature, for a certain system, the partial pressures of N2 = 0.50 atm, H2 = 2.0 atm, and NH3 = 4.0 atm. Is the system at equilibrium? Briefly (in one sentence) explain your answer.
If the system is not at equilibrium, what direction will the system shift (right or left) to reach equilibrium?
S06 ex1 #17
13. A mixture of 0.500 mol H2 and 0.500 mol I2 was placed in a 1.00 L vessel at 430 C. The equilibrium constant Kc for the following reaction is 54.3 at this temperature.
H2 (g) + I2 (g) 2 HI (g)
Calculate the concentrations of H2, I2 and HI at equilibrium.
S06 ex2 #9
14. Consider a 2.0 M solution of lactic acid (HC3H5O3).
a) What is the principal acid-base equilibrium in this solution?
b) What is [H+] in this solution?
S06 ex 2 #10
15. Consider a 2.0 M solution of hydroxylamine (HONH2).
a) What is the principal acid-base equilibrium for this solution?
b) What is [OH–] in this solution?
c) What is the pH in this solution?
F06 ex1 #2
16. Predict the effect of decreasing the temperature on the amount of the reactants in the following reaction (increase, decrease, or stay the same).
C2H2(g) + H2O(g) CH3CHO(g); ∆Hrxn= -151 kJ
F06 ex1 #3
17. a) Write the equilibrium expression in terms of concentration for the following reaction.
SnO2(s) + H2(g) Sn(s) + H2O(g)
Kc=
b) Is the reaction a heterogeneous or a homogeneous reaction?
F06 ex1 #4
18. a) Write the equilibrium expression in terms of pressure for the following reaction.
2SClF5(g) + H2(g) S2F10(g) + 2HCl(g)
Kp=
b) Is the reaction a heterogeneous or a homogeneous reaction?
F06 ex 1 # 6
19. Consider the decomposition of sodium bicarbonate
2NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g)
Does the equilibrium position shift to the right (toward products), to the left (toward reactants), or stay the same as a result of each of the following disturbances?
a) 0.20 atm argon gas is added
b) NaHCO3(s) is added
c) Mg(ClO4)2(s) is added as a drying agent to remove H2O
F06 ex 1 #10
20. Consider the reaction between CH4 and H2S, two components of natural gas:
CH4(g) + 2H2S(g) CS2(g) + 4H2(g)
A sealed reaction vessel initially holds 2.00M CH4, 1.00M H2S, 2.00M CS2, and 2.00M H2 at 960°C. At this temperature, Kc=0.036.
a) Write the expression for the reaction quotient (Qc).
b) In which direction (left or right) will the reaction proceed to reach equilibrium?
c) If [CH4]=3.26M at equilibrium, what will the concentrations of H2S and H2 be at equilibrium?
F06 ex1 #11
21. Calculate Kp for the following equilibrium.
N2(g) + 3H2(g) 2NH3(g); Kc=2.4×10-3 at 1000K
F06 ex 1 #13
22. Calculate Kc for the following reaction:
2NO2(g) N2(g) + 2O2(g)
Use the following data to find the unknown Kc.
½N2(g) + ½O2(g) NO(g) Kc=4.8×10-10
2NO2(g) 2NO(g) + O2(g) Kc=1.1×10-5
S07 ex 1 #6
23. At a given temperature, Kc = 85.0 for the reaction:
SO2(g) + NO2(g) NO(g) + SO3(g)
Initial concentration of gases: [SO2] = 0.040 M, [NO2] = 0.50 M, [NO] = 0.30 M, [SO3] = 0.020 M
a) Determine whether the reaction is at equilibrium. Explain.
b) If the reaction is not at equilibrium, which direction will the reaction proceed?
S07 ex1 #8
24. At 100oC, the equilibrium constant, Kc, for the reaction
CO(g) + Cl2(g) COCl2(g)
is 4.6 x109. Initially 0.20 mol of COCl2 is placed into a 10.0 L flask at this temperature. Determine the concentration of all the species at equilibrium. For full credit, show all work, use units, and report your answer to the correct number of significant figures.
S07 ex 2 #14
25. Kb is 1.7x10–9 for pyridine. Calculate the Ka of the conjugate acid of pyridine at 25 °C. For full credit, show all work, report your final answer to the correct number of significant figures.
S07 ex2 #15
26. Calculate the pH of an aqueous 0.20 M hydroxylamine (H2NOH) solution. Kb for hydroxylamine is 1.1x10–8. For full credit, show all work, report your final answer to the correct number of significant figures.
S07 ex2 #18
27. In the table below, indicate whether the solution formed from dissolving the salt in water is acidic, basic, or neutral.
salt acidic, basic, neutral
KHSO4
BaCl2
NaBrO2
Fe(ClO4)3
NH4NO3