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Q:
For the reaction 2 A + B2 2 AB, the rate of the forward reaction is 0.75 M/s and the rate of the reverse reaction is 0.25 M/s. The reaction is not at equilibrium. In order to attain equilibrium the reaction must proceed in the ________ (forward, reverse) direction in order to achieve equilibrium.
Q:
At an elevated temperature, Kp = 4.2 10-9 for the reaction 2 HBr(g) H2(g) + Br2(g). If the initial partial pressures of HBr, H2, and Br2 are 1.0 10-2 atm, 2.0 10-4 atm, and 2.0 10-4 atm, respectively, what is the equilibrium partial pressure of H2?
Q:
At an elevated temperature, Kp = 0.19 for the reaction 2 NOCl(g) 2 NO(g) + Cl2(g). If the initial partial pressures of NOCl, NO, and Cl2 are 0.50 atm, 0.25 atm, and 0.45 atm, respectively, a net ________ (forward, reverse) reaction must occur in order to achieve equilibrium.
Q:
Kc = 1.2 10-42 at 500 K for the reaction shown below.H2(g) 2 H(g)If [H2] = 1 10-2 M and [H] = 1.2 10-22 M, in order to achieve equilibrium a net reaction must occur from ________ to ________ until Qc = ________.
Q:
Kc = 57.0 at 700 K for the reaction shown below.H2(g) + I2(g) 2 HI(g)If [H2(g)] = [I2(g)] = 0.200 M at equilibrium, the molar concentration [HI((g)] = ________ at equilibrium.
Q:
At 1000 K, Kp = 19.9 for the reaction Fe2O3(s) + 3 CO(g) 2 Fe(s) + 3 CO2(g). What is the value of Kp for the reaction 6 Fe(s) + 9 CO2(g) 3 Fe2O3(s) + 9 CO(g)?
Q:
At 1000 K, Kp = 19.9 for the reaction Fe2O3(s) + 3 CO(g) 2 Fe(s) + 3 CO2(g). What is the value of Kp for the reaction 2 Fe(s) + 3 CO2(g) Fe2O3(s) + 3 CO(g)?
Q:
At 298 K, Kc = 1.7 10-56 for the reaction 3 O2(g) 2 O3(g). What is the value of Kp at this temperature?
Q:
At 298 K, Kp = 2.1 104 for the reaction CO(g) + 2 H2(g) CH3OH(g). What is the value of Kc at this temperature?
Q:
For the reaction CaCO3(s) CaO(s) + O2(g) the equilibrium expression is Kp = ________.
Q:
For the reaction shown below, N2O4 and NO2 have equilibrium concentrations, [N2O4]eq = 2.160 10-4 and [NO2]eq = 1.001 10-3, respectively. The equilibrium constant, Kc, for this reaction equals ________.
N2O4(g) ⇌ 2 NO2(g)
Q:
For the reaction H2(g) + S(s) ⇌ H2S(g), if the rate constant for the forward reaction is greater than the rate constant for the reverse reaction, the value of Kc must be ________ (equal to, greater than, less than) 1.
Q:
In a reversible reaction, when the rate of the forward reaction equals the rate of the reverse reaction, the reaction is at ________.
Q:
A reaction in which reactants form products in the forward reaction and products simultaneously form reactants in the reverse reaction is said to be ________.
Q:
Kc is 1.67 1020 at 25C for the formation of iron(III) oxalate complex ion:Fe3+(aq) + 3 C2O42-(aq) [Fe(C2O4)3]3-(aq).If 0. 0200 M Fe3+ is initially mixed with 1.00 M oxalate ion, what is the concentration of Fe3+ ion at equilibrium?A) 1.44 10-22 MB) 0.0100 MC) 8.35 1019 MD) 6.94 1021 M
Q:
Phosphorus pentachloride decomposes to phosphorus trichloride at high temperatures according to the equation:PCl5(g) PCl3(g) + Cl2(g)At 250 0. 125 M PCl5 is added to the flask. If Kc = 1.80, what are the equilibrium concentrations of each gas?A) [PCl5] = 0.0 0765 M, [PCl3] = 0. 117 M, and [Cl2] = 0. 117 MB) [PCl5] = 0. 0625 M, [PCl3] = 0. 335 M, and [Cl2] = 0. 335 MC) [PCl5] = 1.80 M, [PCl3] = 1.80 M, and [Cl2] = 1.80 MD) [PCl5] = 3.96 M, [PCl3] = 3.83 M, and [Cl2] = 3.83 M
Q:
The equilibrium constant, Kp, equals 3.40 for the isomerization reaction:cis-2-butene trans-2-butene.If a flask initially contains 0.250 atm of cis-2-butene and 0. 145 atm of trans-2-butene, what is the equilibrium pressure of each gas?A) P(cis-2-butene) = 0.0 426 atm and P(trans-2-butene) = 0. 145 atmB) P(cis-2-butene) = 0.0 471 atm and P(trans-2-butene) = 0. 160 atmC) P(cis-2-butene) = 0.0 735 atm and P(trans-2-butene) = 0.250 atmD) P(cis-2-butene) = 0. 0898 atm and P(trans-2-butene) = 0. 305 atm
Q:
At a certain temperature the equilibrium constant, Kc, equals 0.11 for the reaction:2 ICl(g) I2(g) + Cl2(g).What is the equilibrium concentration of ICl if 0. 75 mol of I2 and 0. 75 mol of Cl2 are initially mixed in a 2.0-L flask?A) 0. 22 MB) 0. 28 MC) 0. 45 MD) 0. 56 M
Q:
Cyclohexane, C6H12, undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane, CH3C5H9, according to the equation:C6H12 CH3C5H9If Kc = 0.143 at 25C for this reaction, find the equilibrium concentrations of C6H12 and CH3C5H9 if the initial concentrations are 0.200 M and 0. 075 M, respectively.A) [C6H12] = 0. 041 M, [CH3C5H9] = 0. 041 MB) [C6H12] = 0. 159 M, [CH3C5H9] = 0. 116 MC) [C6H12] = 0. 241 M, [CH3C5H9] = 0. 034 MD) [C6H12] = 0. 253 M, [CH3C5H9] = 0. 022 M
Q:
For the isomerization reaction:
butane ⇌ isobutane
Kp equals 25 at 500C. If the initial pressures of butane and isobutane are 20. atm and 0.0 atm, respectively, what are the pressures of the two gases at equilibrium?
A) P(butane) = 0.77 atm and P(isobutane) = 19.2 atm
B) P(butane) = 0.80 atm and P(isobutane) = 20. atm
C) P(butane) = 19.2 atm and P(isobutane) = 0.77 atm
D) P(butane) = 20 atm and P(isobutane) = 0.80 atm
Q:
At a certain temperature, Kc equals 1.4 102 for the reaction:2 CO(g) + O2(g) 2 CO2(g).If a 3.00-L flask contains 0.400 mol of CO2 and 0.100 mol of O2 at equilibrium, how many moles of CO are also present in the flask?A) 0.555 molB) 0. 185 molC) 0.107 molD) 0.0114 mol
Q:
An equilibrium mixture of CO, O2 and CO2 at a certain temperature contains 0.0010 M CO2 and 0. 0100 M O2. At this temperature, Kc equals 1.4 102 for the reaction:2 CO(g) + O2(g) 2 CO2(g).What is the equilibrium concentration of CO?A) 7.1 10- 7 MB) 8.4 10- 4 MC) 1.4 10-2 MD) 1.2 10-1 M
Q:
At a certain temperature, nitrogen and hydrogen react to form ammonia:N2(g) + 3 H2(g) 2 NH3(g).When initial amounts of N2, H2, and NH3 are mixed, the concentration of NH3 increases. Which statement below is true?A) Kc < QB) Kc > QC) Kc = QD) More information is needed to make a statement about Kc.
Q:
Cyclohexane (C6H12) undergoes a molecular rearrangement in the presence of AlCl3 to form methylcyclopentane (MCP) according to the equation:C6H12 MCPIf Kc = 0.143 at 25C for this reaction, predict the direction in which the system will shift if the initial concentrations of C6H12 and MCP are 0. 0400 M and 0. 0200 M, respectively. The systemA) will shift left.B) will shift right.C) is already at equilibrium.D) is not at equilibrium and will remain in an unequilibrated state.
Q:
The equilibrium constant, Kp, equals 3.40 at 25C for the isomerization reaction:cis-2-butene trans-2-butene.If a flask initially contains 5.00 atm of each gas, in what direction will the system shift to reach equilibrium?A) It will shift left.B) It will shift right.C) The system is already at equilibrium.D) The system is not at equilibrium and will remain in an unequilibrated state.
Q:
The equilibrium constant is equal to 5.00 at 1300 K for the reaction:2 SO2(g) + O2(g) 2 SO3(g).If initial concentrations are [SO2] = 6.00 M, [O2] = 0.45 M, and [SO3] = 9.00 M, the system isA) at equilibrium.B) not at equilibrium and will remain in an unequilibrated state.C) not at equilibrium and will shift to the left to achieve an equilibrium state.D) not at equilibrium and will shift to the right to achieve an equilibrium state.
Q:
For the reaction: N2(g) + 2 O2(g) 2 NO2(g), Kc = 8.3 10-10 at 25C. What is the concentration of N2 gas at equilibrium when the concentration of NO2 is five times the concentration of O2 gas?A) 3.3 10- 11 MB) 1.7 10-10 MC) 6.0 109 MD) 3.0 1010 M
Q:
Which picture (2)-(4) represents the equilibrium mixture when more solid CaO is added?A) picture (2)B) picture (3)C) picture (4)D) All of these
Q:
Which picture (2)-(4) represents the equilibrium mixture when more solid CaCO3 is added?
A) picture (2)
B) picture (3)
C) picture (4)
D) All of these
Q:
Which picture (2)-(4) represents the equilibrium mixture when a catalyst is added?
A) picture (2)
B) picture (3)
C) picture (4)
D) All of these
Q:
Which picture (2)-(4) represents the equilibrium mixture at a higher temperature?
A) picture (2)
B) picture (3)
C) picture (4)
D) None of these
Q:
Which picture (2)-(4) represents the equilibrium mixture after addition of four more CO2 molecules?
A) picture (2)
B) picture (3)
C) picture (4)
D) None of these
Q:
Picture (1) represents the equilibrium mixture for the gas-phase reaction A + B 2 AB at 298 K. If the volume of the equilibrium mixture is decreased, which picture (2)-(4) represents the equilibrium at the reduced volume?A) picture (2)B) picture (3)C) picture (4)D) None of these
Q:
If this reaction is endothermic, which picture (2)-(4) represents the equilibrium mixture at 400 K?
A) picture (2)
B) picture (3)
C) picture (4)
D) None of these
Q:
If this reaction is exothermic, which picture (2)-(4) represents the equilibrium mixture at 400 K?
A) picture (2)
B) picture (3)
C) picture (4)
D) None of these
Q:
If the barrier between the two vessels is removed and the contents of the two vessels are allowed to mix, what will be observed?
A) The reaction will go in the forward direction decreasing the number of A atoms and B atoms and increasing the number of AB molecules.
B) The reaction will go in the forward direction increasing the number of A atoms and B atoms and decreasing the number of AB molecules.
C) The reaction will go in the reverse direction decreasing the number of A atoms and B atoms and increasing the number of AB molecules.
D) The reaction will go in the reverse direction increasing the number of A atoms and B atoms and decreasing the number of AB molecules.
Q:
If the volume of the equilibrium mixture is decreased, what will happen to the number of AB molecules and the number of B atoms?
A) The number of AB molecules and the number of B atoms will both decrease.
B) The number of AB molecules will increase; the number of B atoms will decrease.
C) The number of AB molecules will decrease; the number of B atoms will increase.
D) The number of AB molecules and the number of B atoms will both increase.
Q:
What is the best balanced chemical equation for the reaction?A) A2 + B A2BB) A2 + 2 B A2B2C) A2 + 2 B 2 ABD) 6 A2 + 9 B 3 A2 + 3B + 6 AB
Q:
Which nonequilibrium mixtures will react in the reverse direction to reach equilibrium?
A) reaction mixtures (1) and (2)
B) reaction mixtures (1) and (4)
C) reaction mixtures (2) and (3)
D) reaction mixtures (3) and (4)
Q:
Which nonequilibrium mixture will react in the forward direction to reach equilibrium?
A) reaction mixture (1)
B) reaction mixture (2)
C) reaction mixture (3)
D) reaction mixture (4)
Q:
The following picture represents the equilibrium state for the reaction A2 + B2 2AB. What is the relationship between the rate constant for the forward reaction, kf, and the rate constant for the reverse reaction kr?A) kf < krB) kf = kr = 0C) kf = krD) kf > kr
Q:
The following picture represents the equilibrium state for the reaction A2 + B2 2AB. What is the relationship between the rate constant for the forward reaction, kf, and the rate constant for the reverse reaction kr?A) kf < krB) kf = kr = 0C) kf = krD) kf > kr
Q:
The following picture represents the equilibrium state for the reaction A2 + B2 2AB. What is the relationship between the rate constant for the forward reaction, kf, and the rate constant for the reverse reaction kr?A) kf < krB) kf = kr = 0C) kf = krD) kf > kr
Q:
Shown below is a concentration vs. time plot for the reaction A 2B. For this reaction the value of the equilibrium constant isA) Kc < 1.B) Kc = 0.C) Kc = 1.D) Kc > 1.
Q:
Shown below is a concentration vs. time plot for the reaction A B. For this reaction the value of the equilibrium constant isA) Kc < 1.B) Kc = 0.C) Kc = 1.D) Kc > 1.
Q:
Shown below is a concentration vs. time plot for the reaction A 2B. For this reaction the value of the equilibrium constant isA) Kc < 1.B) Kc = 0.C) Kc = 1.D) Kc > 1.
Q:
Shown below is a concentration vs. time plot for the reaction A B. For this reaction the value of the equilibrium constant isA) Kc < 1.B) Kc = 0.C) Kc = 1.D) Kc > 1.
Q:
Shown below is a concentration vs. time plot for the reaction A 2B. For this reaction the value of the equilibrium constant isA) Kc < 1.B) Kc = 0.C) Kc = 1.D) Kc > 1.
Q:
Shown below is a concentration vs. time plot for the reaction A B. For this reaction the value of the equilibrium constant isA) Kc < 1.B) Kc = 0.C) Kc = 1.D) Kc > 1.
Q:
The following pictures represent mixtures of A2B4 molecules and AB2 molecules, which interconvert according to the equation A2B4 2 AB2. If mixture (1) is at equilibrium, which of the other mixtures are also at equilibrium?A) mixture (2)B) mixture (3)C) mixture (4)D) None of the other mixtures are at equilibrium.
Q:
The following pictures represent mixtures of A2B4 molecules and AB2 molecules, which interconvert according to the equation A2B4 2 AB2. If mixture (1) is at equilibrium, which of the other mixtures are also at equilibrium?A) mixture (2)B) mixture (3)C) mixture (4)D) None of the other mixtures are at equilibrium.
Q:
The following pictures represent mixtures of cis-C2H2X2 molecules and trans-C2H2X2 molecules, which interconvert according to the equation cis-C2H2X2 trans-C2H2X2. If mixture (1) is at equilibrium, which of the other mixtures are also at equilibrium?A) mixture (2)B) mixture (3)C) mixture (4)D) None of the other mixtures are at equilibrium.
Q:
The following pictures represent mixtures of cis-C2H2X2 molecules and trans-C2H2X2 molecules, which interconvert according to the equation cis-C2H2X2 trans-C2H2X2. If mixture (1) is at equilibrium, which of the other mixtures are also at equilibrium?A) mixture (2)B) mixture (3)C) mixture (4)D) None of the other mixtures are at equilibrium.
Q:
The reaction A2 + B2 2 AB has an equilibrium constant Kc = 1.8. The following pictures represent reaction mixtures that contain A2 molecules (shaded) and B2 molecules (unshaded), and AB molecules. Which reaction mixture is at equilibrium?A) reaction mixture (1)B) reaction mixture (2)C) reaction mixture (3)D) reaction mixture (4)
Q:
Which reaction has the smallest equilibrium constant?A) A2 + B2 2 ABB) A2 + C2 2 ACC) A2 + D2 2 ADD) A2 + E2 2 AE
Q:
Which reaction has the largest equilibrium constant?A) A2 + B2 2 ABB) A2 + C2 2 ACC) A2 + D2 2 ADD) A2 + E2 2 AE
Q:
What is the value of the equilibrium constant Kc for the reaction A ⇌ B?
A) Kc = 0.33
B) Kc = 3.0
C) Kc = 12
D) Kc = 27
Q:
Which of these experiments has resulted in an equilibrium state?
A) all of the experiments except experiment (1)
B) all of the experiments except experiment (2)
C) all of the experiments except experiment (3)
D) all of the experiments except experiment (4)
Q:
The reaction below virtually goes to completion because cyanide ion forms very stable complexes with Ni2+ ion:[Ni(H2O)6]2+(aq) + 4 CN-(aq) -> [Ni(CN)4]2-(aq) + 6 H2O(l)At the same time, incorporation of 14C labelled cyanide ion (14CN-) is very rapid:[Ni(CN)4]2-(aq) + 4 14CN-(aq) = [Ni(14CN)4]2-(aq) + 4 CN-(aq)Which statement below is correct with regard to stability and rate of reaction?A) Equilibrium is static.B) Stable species can react rapidly.C) Stable species do not react rapidly.D) Unstable species react rapidly.
Q:
The hexaammine cobalt(III) ion is very unstable in acidic aqueous solution:[Co(NH3)6]3+(aq) + 6 H3O+(aq) -> [Co(H2O)6]4+(aq) + 6 NH4+(aq)However, solutions of hexaammine cobalt(III) can be stored in acidic solution for months without noticeable decomposition. Which statement below about the equilibrium constant and the activation energy for the reaction is true?A) Keq < 103 and Ea is very small.B) Keq > 103 and Ea is very small.C) Keq < 103 and Ea is very large.D) Keq > 103 and Ea is very large.
Q:
Nickel metal can be prepared by the reduction of nickel oxide:NiO(s) + CO(g) CO2(g) + Ni(s)At 936 K, Kp = 4.54 103 and at 1125 K, Kp = 1.58 103. Which statement is true?A) The activation energy decreases with increasing temperature.B) The activation energy increases with increasing temperature.C) The reaction is endothermic.D) The reaction is exothermic.
Q:
At 25C, a certain first order reaction has a rate constant equal to 1.00 10-3 s-1 and an equilibrium constant, Kc, equal to 4.18. What is the rate constant for the reverse reaction?
A) 2.39 10-4 s-1
B) 4.18 10-3 s-1
C) 2.39 102 s-1
D) 4.18 103 s-1
Q:
Find the equilibrium constant for the reaction: A(g) + B(g) 2C(g) at 25C when k equals 1.4 10-12 M-1s-1 for the reaction A(g) + B(g) ⇌ 2C(g) at 25C and k equals 2.7 10-13 M-1s-1 for the reaction: 2 C(g) A(g) + B(g) at 25C.A) 3.8 10-25B) 1.7 10-12C) 1.1 10-12D) 5.2
Q:
A reaction reaches dynamic equilibrium at a given temperature when
A) the amount of products exceeds the amount of reactants.
B) kfwd equals krev.
C) opposing reactions cease and the system is static.
D) the relative amounts of reactants and products are constant and ratefwd = raterev.
Q:
A catalyst increases the rate of a chemical reaction by providing a lower-energy mechanism for the reaction. When this occurs, which one of the following is not affected?
A) activation energy for the forward reaction
B) activation energy for the reverse reaction
C) equilibrium constant
D) rate of the reverse reaction
Q:
A catalyst increases the overall rate of reaction by lowering the activation energy, Ea, for
A) both the forward reaction and the reverse reaction.
B) neither the forward reaction nor the reverse reaction.
C) only the forward reaction.
D) only the reverse reaction.
Q:
Which of the following statements about a catalyst is true?
A) A catalyst changes the position of the equilibrium in a reaction.
B) A catalyst increases the temperature of a reaction.
C) A catalyst is consumed in a chemical reaction.
D) A catalyst provides a lower energy pathway for a reaction.
Q:
Which of the following changes in reaction conditions will not alter the composition of a homogeneous equilibrium mixture of gases in a reaction having unequal moles of gaseous products and reactants?
A) addition of a catalyst
B) addition of reactants or products
C) decreasing the temperature
D) increasing the pressure or volume
Q:
Which will not alter the composition of an equilibrium mixture?
A) addition of a catalyst
B) addition of heat
C) addition of more product
D) addition of more reactant
Q:
The decomposition of nitrosyl bromide is exothermic: 2 NOBr(g) 2 NO(g) + Br2(g). Which of the following changes in reaction condition will shift the reaction to the left?A) add more NOBrB) decrease the temperatureC) increase the container volumeD) None of these
Q:
Calcium carbonate is relatively insoluble and the dissolution reaction is endothermic:CaCO3(s) Ca2+(aq) + CO32-(aq). Which change in reaction condition below will shift the equilibrium to the right?A) add an acid to react with CO32- ionB) add an anion with which Ca2+ is even less soluble than calcium carbonateC) increase the temperatureD) All of these will shift reaction to the right.
Q:
The dissolution of calcium hydroxide is exothermic.Ca(OH)2(s) Ca2+(aq) + 2 OH-(aq) What happens when the solution of Ca(OH)2 is heated?A) The amount of Ca(OH)2(s) decreases.B) The amount of Ca(OH)2(s) increases.C) The amount of Ca(OH)2(s) remains unchanged.D) The Ca(OH)2(s) completely dissolves.
Q:
The overall reaction for photosynthesis can be represented by the following equation:6 CO2(g) + 6 H2O(l) C6H12O6(s) + 6 O2(g)The enthalpy change for this reaction is 2802 kJ. Which of the following changes in condition will shift the equilibrium to the right?A) increase the pressure of O2B) increase the temperatureC) remove CO2 by reaction with CaO(s)D) remove one-half of C6H12O6(s)
Q:
What effect will a change in temperature have on the value of Kp?
A) It will have no effect on the value of Kp.
B) The value of Kp always decreases with an increase in temperature.
C) The value of Kp always increases with an increase in temperature.
D) The value of Kp will decrease or increase with an increase in temperature, depending on whether the reaction is exothermic or endothermic.
Q:
For the reaction shown below, which change in conditions made to the system at equilibrium will result in a net reaction to the right to form more product?C(s) + 2 H2(g) CH4(g) H = -74.8 kJA) adding more CB) increasing the volumeC) lowering the temperatureD) raising the temperature
Q:
Ammonium bromide is a crystalline solid that decomposes endothermically when heated:NH4Br(s) NH3(g) + HBr(g). When solid NH4Br is added to an evacuated flask at 300C, which change in reaction conditions below will cause the equilibrium to shift to the right?A) add more NH3B) add more NH4BrC) decrease the temperatureD) double the volume of the container
Q:
Which change in the system will drive equilibrium to the left in the reaction below?N2O5(g) NO2(g) + NO3(g)A) decrease the amount of NO3B) increase the amount of N2O5C) increase the pressureD) increase the volume
Q:
For the reaction shown below, which change in conditions made to the system at equilibrium will result in a net reaction to the right to form more product?C(s) + 2 H2(g) CH4(g) H = - 74.8 kJA) adding HeB) adding more CC) decreasing the volumeD) increasing the volume
Q:
A crude type of disappearing ink is based on the following endothermic equilibrium:[Co(H2O)6]Cl2 (aq) [CoCl2(H2O)4] (aq) + 2 H2O (l)(colorless) (blue)If the reactant solution is used to write on a piece of paper and the paper is allowed to partially dry, what can be done to bring out the colored handwriting?A) add waterB) decrease the volumeC) put the paper in a freezerD) put the paper in an oven
Q:
The enthalpy for the following reaction is 136 kJ. If the reaction takes place in a closed container, which one of the following reaction conditions will not decrease the concentration of water vapor?2 NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g)A) add CO2B) cool the containerC) decrease the volume of the containerD) remove some NaHCO3