Chemistry: Molecular Nature of Matter and Change, 6th Edition (Silberberg)

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1			In general, Kc for a reaction will remain constant unless there is a change of ________.
			A)	pressure
			B)	time
			C)	volume
			D)	temperature
			E)	concentration(s)
2			Consider the reaction: P4(s) + 5O2(g) ↔ P4O10(s) The reaction quotient Qc is given by
			A)	[P4O10(s)]/([P4(s)][O2]5)
			B)	[P4O10(s)]/[O2]5
			C)	[P4(s)][O2]5/[P4O10(s)]
			D)	[P4O10(s)]/[O2]5
			E)	1/[O2]5
3			Consider the equilibrium reaction: 2NH3(g) ↔ N2(g) + 3H2(g). Kc = 3.0 x 10-3 What is the value of Kc for the reaction below? 0.5N2 + 1.5H2(g) ↔ NH3(g)
			A)	0.0015
			B)	0.0070
			C)	18
			D)	25
			E)	330
4			Consider the equilibrium reaction: 2NH3(g) ↔ 3H2(g) At 500.K, Kc = 5.81 x 10-3. What is the value of Kp at this temperature?
			A)	3.4 x 10-5
			B)	5.8 x 10-3
			C)	7.6 x 10-2
			D)	0.24
			E)	9.8
5			Consider the approach to equilibrium of the reaction: N2O4(g) ↔ 2NO2(g) At equilibrium, the respective concentrations are [N2O4] = 0.0332 mol/L and [NO2] = 0.0837 mol/L. Starting from pure N2O4, which of the following values of Q is the highest that could be achieved before equilibrium is reached?
			A)	3.69
			B)	2.52
			C)	0.252
			D)	0.219
			E)	0.146
6			The equilibrium constant (Kp) for the reaction 2NH3(g) ↔ N2(g) + 3H2(g) is 3.3 x 104. A mixture is made up, with initial partial pressures of: NH3, 50. atm; N2, 100. atm; H2, 100. atm. When this mixture reaches equilibrium
			A)	there will be more N2 and H2 present.
			B)	there will be more NH3 present.
			C)	there will be less N2 but more H2 present.
			D)	there will be less NH3 and less N2 present.
			E)	This system cannot reach equilibrium from the given starting conditions.
7			Consider the equilibrium reaction: 2SO2(g) + O2(g) ↔ 2SO3(g)The concentrations of these gases at equilibrium are as follows: [SO2] = 0.20 mol/L [O2] = 0.80 mol/L, [SO3] = 0.43 mol/L. What is the equilibrium constant Kc for the reaction?
			A)	5.8
			B)	1.7
			C)	2.7
			D)	0.37
			E)	none of the above
8			Ammonium carbamate (NH4CO2NH2) decomposes according to the equation: NH4CO2NH2(s) ↔ 2NH3(g) + CO2(g) Solid NH4CO2NH2 is introduced into a sealed vessel and allowed to equilibrate. At equilibrium, the total pressure in the vessel is 0.117 atm. What is the value of the equilibrium constant Kp for the reaction at this temperature?
			A)	0.039
			B)	3.0 x 10-3
			C)	2.4 x 10-4
			D)	1.2 x 10-3
			E)	6.4 x 10-3
9			Gaseous hydrogen fluoride can be produced by the direct reaction of hydrogen gas with fluorine gas, with an equilibrium constant Kc = 1.30 x 102. H2(g) + F2(g) ↔ 2HF(g) An experiment is started by adding 2.00 mol each of H2, F2 and HF to a 0.500 L sealed reaction vessel. Predict the direction in which the reaction will proceed toward equilibrium, and the equilibrium concentration of the HF(g).
			A)	The reaction will proceed to the left; [HF] = 0.0900 mol/L.
			B)	The reaction will proceed to the left; [HF] = 3.10 mol/L.
			C)	The reaction will proceed to the right; [HF] = 11.8 mol/L.
			D)	The reaction will proceed to the right; [HF] = 10.2 mol/L.
			E)	The reaction will proceed to the right; [HF] = 4.91 mol/L.
10			Ethene (C2H4) undergoes catalytic hydrogenation to form ethane (C2H6) according to the equation: C2H4(g) + H2(g) ↔ C2H6(g) If 6.0 moles of ethene and 6.0 moles of hydrogen are introduced into a 2.0 L sealed vessel and allowed to equilibrate at 200ºC, what is the equilibrium concentration of the ethene (C2H4) in the vessel? (Kc = 6.6 x 108 at this temperature)
			A)	4.8 x 103 mol/L
			B)	9.5 x 10-5 mol/L
			C)	2.0 x 10-8 mol/L
			D)	6.7 x 10-5 mol/L
			E)	2.5 x 104 mol/L
11			Consider the gas phase reaction: 2NH3(g) ↔ N2(g) + 3H2(g) At a certain temperature, Kc is 2.2 x 10-3. The reaction is started by placing a 0.040 mole sample of ammonia in an empty one liter flask. When equilibrium is established, how many moles of N2 will be present?
			A)	0.010 mol
			B)	0.012 mol
			C)	0.014 mol
			D)	0.016 mol
			E)	0.030 mol
12			Consider the equilibrium: 2NOBr(g) ↔ 2NO(g) + Br2(g) ↔ H°rxn = -47.3 kJ Which of the following actions will cause the equilibrium to be shifted to the left (in favor of reactants)?
			A)	adding some argon gas to increase the total pressure in the vessel
			B)	adding some gaseous NOBr
			C)	adding a catalyst
			D)	doubling the volume of the container
			E)	raising the temperature
13			At elevated temperatures, solid silicon reacts with chlorine gas to form gaseous SiCl4: Si(s) + 2Cl2(g) ↔ SiCl4(g) If a reaction mixture is at equilibrium, which of the following actions will produce more SiCl4?
			A)	adding more solid silicon
			B)	increasing the pressure
			C)	removing some Cl2
			D)	increasing the volume
			E)	adding a catalyst
14			Consider the following reaction at equilibrium: NO2(g) + CO(g) ↔ NO(g) + CO2(g) If the volume of the system is reduced at constant temperature, what change, if any, will occur in the equilibrium?
			A)	a shift to produce more NO
			B)	no change
			C)	a shift to produce more CO
			D)	a shift to produce more NO2
			E)	The sign of ΔHºrxn must be given in order to answer this question.
15			Consider the synthesis of ammonia from its elements: N2(g) + 3H2(g) ↔ 2NH3(g) ↔ H°rxn = -92 kJ At a temperature of 500.K, the value of Kc is 172. Calculate its value at 600.K.
			A)	270
			B)	180
			C)	160
			D)	96
			E)	4.3