Equilibrium Constant

H2(g) + I2(g) ⇄ 2HI(g) A 1.0mol sample of H2(g) and a 1.0mol sample of I2(g) are placed in a previously evacuated 1.0L container and allowed to reach the equilibrium shown above. If the equilibrium concentration of HI(g) is 0.40M, which of the following is the value of the equilibrium constant?

• 0.16

• 0.25

• 0.44

• 1.0

COCl₂(g)   ⇄   CO(g) + Cl₂(g)

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 K_p for the reaction at 690 K?

• 0.040

• 0.050

• 0.80

• 1.0

2X(g) + Y(g) ⇄ 3Z(g)

The reaction mixture represented above is at equilibrium at 298 K, and the molar concentrations are [X] = 2.0 M, [Y] = 0.5 M, and [Z] = 4.0 M. What is the value of the equilibrium constant for the reaction at 298 K ?

• 0.50

• 2.0

• 4.0

• 16

• 32

Tags

NGSS.HS-PS1-7

A(g) and B(g) react to form C(g), according to the balanced equation above. In an experiment, a previously evacuated rigid vessel is charged with A(g), B(g), and C(g), each with a concentration of 0.0100M. The following table shows the concentrations of the gases at equilibrium at a particular temperature. [A]eq [B]eq [C]eq 0.0180 0.0140 0.0020 If the experiment is repeated at a higher temperature at which Kc is larger, which of the following best describes the effect of the temperature change on the concentrations of the gases at equilibrium?

• [A]eq, [B]eq, and [C]eq will all increase because Kc increased.

• [A]eq and [B]eq will remain constant, but [C]eq will increase because Kc increased.

• There will be a decrease in [A]eq that will be two times the decrease in [B]eq because A and B react in a 2-to-1 ratio.

• There will be an increase in [A]eq that will be two times the increase in [B]eq because A and B react in a 2-to-1 ratio.

Tags

NGSS.HS-PS1-5

NO2(g) ⇄ N2O4(g)

dark brown colorless

The dimerization of NO2(g) , an exothermic process, is represented by the equation above.

A 0.0300 mol sample of NO2(g) is placed in a rigid 1.00 L reaction vessel and allowed to reach equilibrium at a certain temperature. What is the value of Kc at this temperature if 0.00500 mol of N2O4(g) is present at equilibrium?

• 0.0080

• .250

• 4.00

• 12.5

NO2(g) ⇄ N2O4(g) dark brown colorless The dimerization of NO2(g) , an exothermic process, is represented by the equation above. A 0.0688 mol sample of NO2(g) is placed in a rigid 1.00 L reaction vessel and allowed to reach equilibrium at a certain temperature. What is the value of Kc at this temperature if 0.0133 mol of N2O4(g) is present at equilibrium?

• .134

• .315

• 4.32

• 7.47

PCl₅(g)   ⇄    PCl₃(g) + Cl₂(g)

PCl₅(g) decomposes into PCl₃(g) and Cl₂(g) according to the equation above. A pure sample of PCl₅(g) is placed in a rigid, evacuated 1.00 L container. The initial pressure of the PCl₅(g) is 1.00 atm. The temperature is held constant until the PCl₅(g) reaches equilibrium with its decomposition products. The figures below show the initial and equilibrium conditions of the system. Which of the following statements about Kp, the equilibrium constant for the reaction, is correct?

• Kp > 1

• Kp < 1

• Kp = 1

• It cannot be determined whether Kp > 1, Kp < 1, or Kp = 1 without additional information.

Tags

NGSS.HS-PS1-5

Equimolar samples of CH₃OH(l) and C₂H₅OH(l) are placed in separate, previously evacuated, rigid 2.0 L vessels. Each vessel is attached to a pressure gauge, and the temperatures are kept at 300 K. In both vessels, liquid is observed to remain present at the bottom of the container at all times. The change in pressure inside the vessel containing CH₃OH(l) is shown below. The value of K_p for the evaporation of CH₃OH(l) at 300 K is closest to

• 0.04

• 0.2

• 5

• 30

Tags

NGSS.HS-PS1-4

The decomposition of HI(g) at 298K is represented by the equilibrium equation above. When 100.torr of HI(g) is added to a previously evacuated, rigid container and allowed to reach equilibrium, the partial pressure of I2(g) is approximately 3.7torr. If the initial pressure of HI(g) is increased to 200.torr and the process is repeated at the same temperature, which of the following correctly predicts the equilibrium partial pressure of I2(g), and why?

• PI2≈14 torr because it is directly proportional to the square of the initial pressure of HI

• PI2≈0.073 torr because it is inversely proportional to the square of the initial pressure of HI

• PI2≈7.4 torr because it is directly proportional to the initial pressure of HI

• PI2≈1.9 torr because it is inversely proportional to the initial pressure of HI

Tags

NGSS.HS-PS1-5

The equilibrium constant expression for the reaction BrF_5(g) —> Br_2(g) + F_2(g) is

• Kc = [Br₂] [F₂] / [BrF_5]

• Kc = [BrF₅]² / [Br₂][F₂]⁵

• Kc = [Br₂] [F₂]⁵ / [BrF₅]²

• Kc = 2[BrF₅]² / ([Br₂] × 5[F₂]⁵)

• Kc = [Br₂] [F₂]² / [BrF₅]⁵