AP Chemistry Equilibrium

An aqueous equilibrium mixture of CoCl4 , CoBr4 , Cl-, and Br- is present in a flask at 25°C. Which action below will change the value of the equilibrium constant from that which currently describes the concentration relationships of the four species above?

• add more Cl- to the solution

• add more CoBr42- to the solution

• put the flask into an 80°C water bath

• add more Br- to the solution

• add more CoCl42- to the solution

Tags

NGSS.HS-PS1-5

The reaction quotient for a system is 729. If the equilibrium constant for the system is 36, what will happen as equilibrium is approached?

• There will be a net gain in product.

• There will be a net gain in reactant.

• There will be a net gain in both product and reactant.

• There will be no net gain in either product or reactant.

• The equilibrium constant will decrease until it equals the reaction quotient.

The diagram above represents H_2(g) and N_2(g) in a closed container. Which of the following diagrams would represent the results if the reaction shown below were to proceed as far as possible?

N_2(g) + 3H_2(g) ↔ 2NH_3(g)

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Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-3

N₂O_4(g) 2NO_2(g)

N₂O_4(g) decomposes into NO_2(g) according to the equation above. A pure sample of N₂O_4(g) is placed into a rigid, evacuated, 0.500 L container. The initial pressure of the N₂O_4(g) is 760 atm. The temperature is held constant until the N₂O_4(g) reaches equilibrium with its decomposition products. The figure below shows how the pressure of the system changes while reaching equilibrium.Which diagram is an appropriate description of the partial pressure of N2O4(g) when N2O4(g)

is rapidly injected, at time = 0, into the container after equilibrium is established?

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Tags

NGSS.HS-PS1-5

What change was made to the equilibrium system at 15 minutes and what impact did this have on the system?

• F2(g) was added and the reaction shifted forward.

• F2(g) was added and the reaction shifted in reverse.

• F2(g) was removed and the reaction shifted forward.

• F2(g) was removed and the reaction shifted in reverse.

• CO2(g) was added and the reaction shifted forward.

Tags

NGSS.HS-PS1-5

Given the following information, which of the statements is true:

• H⁺ is incapable of being oxidized or reduced

• Sn²⁺ is the weakest oxidizing agent

• Ni_(s) is the strongest oxidizing agent

• Li_(s) is the strongest reducing agent

• Li⁺_(aq) is the strongest reducing agent

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

Find the standard reduction potential for the reaction: In⁺³ + 3e- → In

• 0.34 V

• –0.34 V

• 1.02 V

• –1.02 V

• 0.00 V

Tags

NGSS.HS-PS1-7

Consider an electrochemical cell based on the reaction: 2H⁺_(aq) + Sn_(s) → Sn²⁺_(aq) + H_2(g) Which of the following actions would not change the measured cell potential?

• lowering the pH in the cathode compartment

• addition of more tin metal to the anode compartment

• increasing the tin (II) ion concentration in the anode compartment

• increasing the pressure of hydrogen gas in the cathode compartment

• any of these things will increase the measure cell potential

Tags

NGSS.HS-PS1-4

2N2O_{5 (g)} → 2N_{2 (g)} + 5O_{2 (g)}

Dinitrogen pentoxide decomposes in a first- order reaction with a half-life of 7 minutes at 230°C according to the equation above.

If N₂O₅ is added to an evacuated flask to a pressure of 800 torr at 230°C, what is the total pressure in the flask after 14 minutes?

• 200 torr

• 800 torr

• 1400 torr

• 2300 torr

• 4200 torr

Tags

NGSS.HS-PS1-5

An unknown acid is dissolved in 25 mL of water and titrated with 0.100 M NaOH. The results are shown in the titration curve above. Which of the following could be the unknown acid?

• Fluoroacetic acid, pK_a = 2.6

• Glycolic acid, pK_a = 3.8

• Propanoic acid, pK_a = 4.9

• Hypochlorous acid, pK_a = 7.5

• Boric acid, pK_a = 9.3

Tags

NGSS.HS-PS1-7