CHM 152 – Equilbrium实地调查
Equilibrium Constant, K c and K p
1. Once a system has reached equilibrium, are the following true or fal?
a. The reaction is finished, no more products are forming. __ fal __
b. The concentrations of the reactants and the products are equal. fal __
c. The concentrations are no longer changing. _ true _
d. The reaction is not over, but will continue forever if isolated. _ true _
e. The speed at which products are made equals the speed at which reactants form. true
2. What is equal at equilibrium? ____forward and rever rates _____
3. What general information can be gathered by obrving the magnitude of the equilibrium constant? Whether a reaction is reactant- or product-favored.
4. Answer the following for the reaction of NO gas with chlorine gas to produce NOCl gas. Write out the balanced reaction, and the K c and K p expressions.
2 NO(g) + Cl 2(g) D 2 NOCl(g) K c = ]
Cl [[NO]NOCl][222
K p = ))(P (P P 2Cl 2NO 2NOCl 5. Write the equilibrium expression K c for the reaction between potassium phosphate and calcium nitrate in water. Show the balanced reaction.
2 K 3PO 4(aq) +
3 Ca(NO 3)2(aq) D 6 KNO 3(aq) + Ca 3(PO 4)2(s)
K c = 3
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3])[Ca(NO ]PO [K ][KNO K p = NA
6. Write the equilibrium expression K c for the reaction between sodium carbonate and calcium hydr
oxide in water.
Na 2CO 3(aq) + Ca(OH)2(aq) D 2 NaOH(aq) + CaCO 3(s)
K c = [NaOH]2 / [Na 2CO 3][ Ca(OH)2]
7 .Write the expression for K c for the reaction: Ag +(aq) + 2 NH 3(aq) D Ag(NH 3)2+(aq)
夸奖女孩子漂亮的词语K c = [Ag(NH 3)2+] / [Ag +][(NH 3)2]
8. Write the expression for K p for the reaction : H 2(g) + Br 2(l) D 2 HBr(g)
K p = P HBr 2 / (P H2)
9. Write the expression for K p for the reaction: CO 2(g) + CaO(s) D CaCO 3(s)笔下生风
K p = 1 / P CO2
10. Write K c expressions for the following reactions:
a) 3 O2 (g) D 2 O3 (g) K c = [(O3)2] / [(O2)3]
b) N2 (g) + 3 H2 (g) D 2 NH3 (g) K c = [(NH3)2] / [N2][(H2)3]
c) H2 (g) + I2 (g) D 2 HI (g) K c = [(HI)2] / [H2][I2]
d) PCl5 (g) D PCl3 (g) + Cl2 (g) K c = [PCl3][Cl2] / [PCl5]
e) SO2 (g) + ½ O2 (g) D SO3 (g) K c = [SO3] / [SO2][(O2)1/2]
11. Write K p expressions for each of the following reactions:
a) Ni(s) + 4CO(g) D Ni(CO)4(g) K p = P Ni(CO)4 / (P CO)4
b) 5CO(g) + I2O5(s) D I2(g) + 5CO2(g) K p = (P I2)(P CO2)5 / (P CO)5
c) Ca(HCO3)2(aq) D CaCO3(s) + H2O(l) + CO2(g) K p = P CO2
d) AgCl(s) D Ag+(aq) + Cl−(aq) K p = 1
12. Arrange the reactions in order of their increasing tendency to proceed toward completion: _B_ _C_ _D_ _A_
(a) 4NH3(g) + 3O2(g) D 2N2(g) + 6H2O(g) K p = 1 x 10228 atm
(b) N2(g) + O2(g) D 2NO(g) K p = 5 x 10-31
(c) 2HF(g) D H2(g) + F2(g) K p = 1 x 10-13
(d) 2NOCl(g) D 2NO(g) + Cl2(g) K p = 4.7 x 10-4 atm
13. Nitrogen dioxide dimerizes to form dinitrogen tetraoxide: 2 NO2(g) D N2O4(g)
Calculate the value of K c, given that the gas pha equilibrium constant, K p, for the reaction is 1.3
× 103 at 273 K. (R = 0.08206 L·atm/mol·K)
Δn = -1; K p = K c(RT)Δn = 2.9 x 104
Calculating K, Q, ICE tables
14.Answer the following for the reaction of NO gas with chlorine gas to produce NOCl gas.
Calculate K p and K c at 25.0o C given the pressure of NO gas is 1.56 atm, chlorine gas is 0.887 atm, and NOCl gas is 3.45 atm.
K p = = 5.51398 = 5.51 K c = = 135
15.Calculate the equilibrium constant for this reaction: 2 PO2Br (aq) D 2 PO2 (aq) + Br2 (aq)
Given: [PO2Br] = 0.0255M, [PO2] = 0.155M, and [Br2] = 0.00351M at equilibrium.
K = [PO2]2 [Br2] / [PO2Br]2 = (0.155)2(0.00351) / (0.0255)2 = 0.130
16.Calculate the equilibrium constant K c for this unbalanced reaction: 2 SO3 (g) D 2 SO2 (g) + O2 (g)
Given: [SO3] = 0.0255M, [SO2] = 1.08M, and [O2] = 1.45M at equilibrium.
K c = = = 2.60 x 103
17. U the equilibrium reaction: H2 (g) + I2 (g) D 2 HI (g) to calculate K c for each of the ts of equilibrium concentrations below.
a. [H2] = 0.0505 M
[I2] = 0.0498 M
[HI] = 0.349 M K c = 48.4
b. [H2] = 0.00560 M
社会图片霸气图片
[I2] = 0.000590 M
[HI] = 0.0127 M K c = 48.8
c. [H2] = 0.00460 M
[I2] = 0.000970 M
[HI] = 0.0147 M K c = 48.4
What do you notice about the 3 K c values? They’re all about the same value (or should be clo).
18. For the combination reaction: H2 (g) + I2 (g) D 2 HI (g), calculate all three equilibrium concentrations when [H2]o = [I2]o = 0.200 M and K c = 64.0.
ICE table: x = 0.160 M
[H2] = 0.200 - x = 0.040 M
[I2] = 0.200 - x = 0.040 M
[HI] = 2 (x) = 0.320 M
19. For the combination reaction, PCl3 (g) + Cl2 (g) D PCl5 (g), calculate all three equilibrium concentrations when K c = 16.0 and [PCl5]o = 1.00 M.
Bad problem – no solution. You can t up the ICE table and equilibrium expressions, but the solution doesn’t work out with the numbers. I’ll fix it later….
ICE table: K c = (1.00 - x) / x2 = 16.0
20. For the decomposition reaction, COCl2 (g) D CO (g) + Cl2 (g), calculate all three equilibrium concentrations when K c = 0.680 with [CO]o = 0.500 and [Cl2]o = 1.00 M.
ICE table: Kc = (0.500 – x)(1.00 – x) / x = 0.680
x = (2.18 ± 1.66) / 2 = 0.26048
[COCl2] eq = 0.260 M, [CO] eq = 0.500 – 0.260 = 0.240 M, [Cl2] eq = 1.00 – 0.260 = 0.740 M
21. We place 0.064 mol N2O4 (g) in a 4.00 L flask at 200 K. After reaching equilibrium, the concentration of NO2(g) is 0.0030 M. What is K c for the reaction N2O4(g) D 2 NO2(g)?
x = 0.0015
[N2O4]eq = 0.0145, [NO2]eq = 0.0030
K c = 6.2 x 10-4
22. Carbonyl bromide decompos to carbon monoxide and bromine: COBr2(g) D CO(g) + Br2(g)
K c is 0.190 at 73o C. If an initial concentration of 0.330 M COBr2 is allowed to equilibrate, what
are the equilibrium concentrations of COBr2, CO, and Br2?
K c = x2 / (0.330 – x) = 0.190
x = 0.1728木兰八景
[COBr2]eq = 0.330 – 0.1728 = 0.157 M; [CO]eq = [Br2]eq = 0.173 M
23. H2(g) + CO2(g)D H2O(g) + CO(g)
a)It is found at 986o C that there are 11.2 atm each of CO and water vapor and 8.8atm each of H2 and
CO2 at equilibrium. Calculate the equilibrium constant.
K p = (11.2)(11.2) / (8.8)(8.8) = 1.6198 = 1.62
b)If there were 8.8 moles of H2 and CO2 in a 500.0mL container at equilibrium, how many moles of
CO(g) and H2O(g) would be prent?
K c = 1.62 = x2 / y2 y = 8.8 moles / 0.5000 L = 17.6 1.62 = x2 / 309.76 x = 11.2 moles 24. Consider the equilibrium: 2N 2O(g) + O2(g) 4NO(g)
3.00 moles of NO(g) are introduced into a 1.00-Liter evacuated flask. When the system comes to
equilibrium, 1.00 mole of N2O(g) has formed. Determine the equilibrium concentrations of each substance. Calculate the K c for the reaction bad on the data.
海尔老总2N 2O(g) + O2(g) 4NO(g)
0 0 3.00 M
+2x +x -4x
2x x 3.00 – 4x K c = (3.00 – 4x)4 / (2x)2(x)
1.00 mole of N2O in 1.00 L = 1.00 M; Therefore, 2x = 1.00 M and x = 0.50 M
带蛇的成语K c = (3.00 – 4x)4 / (2x)2(x) = (3.00 – 4*0.5)4 / (2*0.5)2(0.5) = 2
[NO]eq = [N2O]eq = 1.00 M; [O2]eq = 0.50 M
25. For the reaction: SiH4(g) + O2(g)D SiO2(g) + H2O(g)
a. Balance the equation. SiH4(g) + 2 O2(g)D SiO2(g) + 2 H2O(g)
b. Write the equilibrium expression for the forward reaction:
K c = [SiO2][H2O]2 / [SiH4][O2]2
c. Write the equilibrium expression for the rever reaction:
K c = [SiH4][O2]2 / [SiO2][H2O]2
岩浆图片d. What is the equilibrium constant in the forward direction if [SiH4] = 0.45M; [O2] = 0.25M; [SiO2] =
0.15M; and [H2O] = 0.10M at equilibrium?
K f = (0.15)(0.10)2 / (0.45)(0.25)2 = 0.053
e. What is the equilibrium constant in the rever reaction? K f = (0.45)(0.25)2 / (0.15)(0.10)2 = 19
f. If [SiH4] = 0.34M; [O2] = 0.22M; [SiO2] = 0.35M; and [H2O] = 0.20M, what would be the reaction quotient (Q) in the forward direction?
Q = (0.35)(0.20)2 / (0.34)(0.22)2 = 0.85
g. Which direction will the reaction in part f go? (Toward products or reactants?)
Toward reactants
26.Phosphorus pentachloride decompos into phosphorus trichloride and chlorine gas. What is the initial
concentration of phosphorus pentachloride if at equilibrium the concentration of chlorine gas is
0.500M? Given: K c = 10.00 (Hint: ICE table)
PCl5D PCl3 + Cl2
I x 0 0 10.00 = (0.500)2 / (x-0.500)
C -0.500 +0.500 +0.500 10.00 x – 5 = 0.25
E (x-0.500) (0.500) (0.500) x = 0.525 M = [PCl5]
