Chemistry MCQ Final

A 0.10 mol sample of each of the four species in the reaction represented above is injected into a rigid, previously evacuated 1.0 L container. Which of the following species will have the highest concentration when the system reaches equilibrium? A. H2S(g) B. CH4(g) C. CS2(g) D. H2(g)

A.

A 1.0 mol sample of CO(g) and a 1.0 mol sample of H2(g) are pumped into a rigid, previously evacuated 2.0 L reaction vessel at 483 K. Which of the following is true at equilibrium? A. [H2] = 2[CO] B. [H2] < [CO] C. [CO] = [CH3OH] < [H2] D. [CO] = [CH3OH] = [H2]

A.

A mixture of CO(g) and H2(g) is pumped into a previously evacuated 2.0 L reaction vessel. The total pressure of the reaction system is 1.2 atm at equilibrium. What will be the total pressure of the system if the volume of the reaction vessel is reduced to 1.0 L at constant temperature? A. Less than 1.2 atm B. Greater than 1.2 atm but less than 2.4 atm C. 2.4 atm D. Greater than 2.4 atm

A.

For which of the following equilibrium systems represented below will the amount of product(s) at equilibrium increase if the volume of the reaction is increased at a constant temp? A. PCl5(g) --> PCl3(g) + Cl(g) B. 2 NO(g) + O2(g) --> 2 NO(g) C. N2(g) + O2(g) --> 2 NO(g) D. 2 CO(g) --> C(s) + CO2(g)

A.

A certain gas, XY(g), decomposes as represented by the equation above. A sample of each of the three gases is put in a previously evacuated container. The initial partial pressures of the gases are shown in the table below. (Table) The temp of the reaction mixture is held constant. In which direction will the reaction proceed? A. The reaction will form more products B. The reaction will form more reactant C. The mixture is at equilibrium, so there will be no change D. Cannot be determined unless the volume of the container is known

B.

COCl2(g) decomposes according to the equation above. When pure COCl2(g) is injected into a rigid, previously evacuated flask at 690 K, the pressure in the flask is initially 1.0 atm. After the reaction reaches equilibrium at 690 K, the total pressure in the flask is 1.2 atm. What is the value of Kp for the reaction at 690? A. 0.040 B. 0.050 C. 0.80 D. 1.0

B.

The amount of H2(g) present in a reaction mixture at equilibrium can be maximized by A. Increasing the temperature and increasing the pressure by decreasing the volume. B. Increasing the temperature and decreasing the pressure by increasing the volume. C. Decreasing the temperature and increasing the pressure by decreasing the volume. D. Decreasing the temperature and decreasing the pressure by increasing the volume.

B.

The reaction system represented above is at equilibrium. Which of the following will decrease the amount of CaO(s) in the system? A. Increasing the volume of the reaction vessel at constant temperature B. Lowering the temperature of the system C. Removing some CO2(g) at constant temperature D. Removing some CaCO3(s) at constant temperature

B.

Which of the following statements best helps explain why the contents of the tube containing the equilibrium mixture turned a lighter color when the tube was placed into an ice bath? A. The forward reaction is exothermic B. The forward reaction is endothermic C. The ice bath lowered the activation energy D., The ice bath raised the activation energy

B.

if P(N2O4) is 1.33 atm when the system is at equilibrium at 70 C which is P(NO2) A. 0.44 atm B. 2.0 atm C. 2.3 atm D. 4.0 atm

B.

At 450C, 2.0 moles of each of H2(g), I2(g) are combined in a 1.0L rigid container. The value of Kc at 450C is 50. Which of the following will occur as the system moves toward equilibrium? A. More H2(g) and I2(g) will form B. More HI(g) will form C. The total pressure will decrease D. No net reaction will occur, because the number of molecules is the same on both sides

B>

A 1.0 mol sample of X(g) and a 1.0 mol sample of Q(g) are introduced into an evacuated, rigid 10.0 L container and allowed to reach equilibrium at 50 C according to the equation above. At equilibrium, which of the following is true about the concentrations of the gases? A. [R] = 1/2[Q] B. [Q] = 1/2[X] C. [R] = [Z] > [Q] D [X] = [Q] = [R] = [Z]

C.

A 2.0 mol sample CO(g) and 2.0 mol sample H2O(g) are introduced into a previously evacuated 100 L rigid container, and the temperature is held constant as the reaction represented above reaches equilibrium. Which of the following is true at equilibrium? A. [H2O] > [CO] and [CO2] > [H2] B. [H2O]>[H2] C. [CO2]>[CO] D. [CO] = [H2O] = [CO2] = [H2]

C.

A sealed rigid vessel contains BaO2(s) in equilibrium with BaO(s) and O2(g) as represented by the equation above. Which of the following changes will increase the amount of BaO2(s) in the vessel? A. Removing a small amount of O2(g) B. Removing a small amount of BaO(s) C. Adding He gas to the vessel D. Lowering the temperature

C.

At a certain point in time, a 1.00 L rigid reaction vessel contains 1.5 mol of PCl3(g), 1.0 mol of Cl2(g), and 2.5 mol of PCl5(g). Which of the following described how the measured pressure in the reaction vessel will change and why it will change that way as the reaction system approaches equilibrium at constant temperature? A. The pressure will increase because Q < K B. The pressure will increase because Q > K C. The pressure will decrease because Q < K D. The pressure will decrease because Q > K

C.

Equal volumes of 0.1 M AgNO3(aq) and 2.0 M NH3(aq) are mixed and the reactions represented above occur. Which Ag species will have the highest concentration in the equilibrium system shown below, and why? A. Ag(aq), because K3 = 4 B. Ag(aq), because K1 < K2 C. Ag(NH3)2(aq), because K3 = 1.6 x 10^7 D. Ag(NH3)2(aq), because K1 < K2

C.

Equimolar samples of each of three gases, H2, I2, and HI are introduced into a 3.0L container that is heated to 600C. According to the information above, which of the following will occur as the system approaches equilibrium? A. More H2(g) will be produced because Q > Kc B. More I2(g) will be produced because Q < Kc C. More HI(g) will be produced because Q < Kc D. No change will occur because Q = K

C.

Which of the following explains the effect on the equilibrium constant Kc, when the temperature of the reaction system is increased to 650 K? A. Kc will increase because the activation energy of the forward reaction increases more than that of the reverse reaction. B. Kc will increase because there are more reactant molecules than product molecules. C. Kc will decrease because the reaction is exothermic. D. Kx is constant and will not change.

C.

Which of the following shows the relationship between K1 and K2, in the reactions above? A. K2=(K1)^2 B. C. K2=1/(K1)^2 D.

C.

Based on the information above, which of the following expressions represents the equilibrium constant K, for the reaction represented by the equation below? A. K = (K1)(Ka)(Kw) B. K = (K1)(Ka)/Kw C. K = K1/(Ka)(Kw) D. K= (K1)(Kw)/Ka

D.

For which of the following reaction mixtures at equilibrium would reducing the volume of the container at constant temperature cause the equilibrium to shift toward the products? A. SrCO3(s) --> SrO(s) + Co2(g) B. C(s) + CO2(g) --> 2 CO(g) C. CO(g) + H2O(g) --> CO2(g) + H2(g) D. 2NO2(g) --> N2O4(g)

D.

NH3(g) was synthesized at 200C in the presence of a powdered Os(s) catalyst, leading to the equilibrium system represented above. Which of the following changes would result in more NH3(g) in the mixture after equilibrium is reestablished? A. Replacing the powdered Os(s) with a solid cube of Os(s) of the same total mass B. Increasing the temperature of the system to 250C at constant pressure. C. Removing some H2(g) D. Adding some N2(g)

D.

The equilibrium constant for the gas phase reaction above is 95 at 25C. What is the value of the equilibrium constant for the following reactions at 25C? A. (95)^2 B. (95)^1/2 C. 1/95 D. 1/(95)^2

D.

When 4.00 mol of X(g) and Y(g) are placed in a 1.00 L vessel and allowed to react at constant temperature according to the equation above, 6.00 mol of Z(g) is produced. What is the value of the equilibrium constant, Kc=? A. 3 B. 6 C. 12 D. 36

D.