AP Chem Acids Bases Buffer Review

Cu(s) + 2 Ag⁺ ↔ Cu²⁺ + 2 Ag(s)

If the equilibrium constant for the reaction above is 3.7 x 10¹⁵, which of the following correctly describes the standard voltage, E°, and the standard free energy change, ΔG°, for this reaction?

• E° is positive and ΔG° is negative.

• E° is negative and ΔG° is positive.

• E° and ΔG° are both positive.

• E° and ΔG° are both negative.

Tags

NGSS.HS-PS1-4

CuO(s) + H₂(g) ↔ Cu(s) + H₂O(g)

ΔH = –2.0 kilojoules mol^–1

When the substances in the equation above are at equilibrium at pressure P and temperature T, the equilibrium can be shifted to favor the products by

• increasing the pressure by means of a moving piston at constant T

• increasing the pressure by adding an inert gas such as nitrogen

• decreasing the temperature

• adding a catalyst

Tags

NGSS.HS-PS1-5

For the reaction A(g) ↔ B(g) + C(g), the equilibrium constant, Kp, is 2 x 10^–4 at 25 °C. A mixture of the three gases at 25 °C is placed in a reaction flask and the initial pressures are P_A = 2 atmosphere, P_B = 0.5 atmosphere, and P_C = 1 atmosphere. At the instant of mixing, which of the following is true for the reaction as written?

• ΔG < 0

• ΔG > 0

• ΔG° = 0

• ΔG° < 0

Tags

NGSS.HS-PS1-4

In which of the following systems would the number of moles of the substances present at equilibrium NOT be shifted by a change in the volume of the system at constant temperature?

• CO(g) + NO(g) ↔ CO₂(g) + ½ N₂(g)

• N₂(g) + 3 H₂(g) ↔ 2 NH₃(g)

• N₂(g) + 2 O₂(g) ↔ 2 NO₂(g)

• NO(g) + O₃(g) ↔ NO₂(g) + O₂(g)

Which of the following must be true for a reaction that proceeds spontaneously from initial standard state conditions?

• ΔG° > 0 and K_eq > 1

• ΔG° > 0 and K_eq < 1

• ΔG° < 0 and K_eq > 1

• ΔG° < 0 and K_eq < 1

H₂C₂O₄ + 2 H₂O ↔ 2 H₃O⁺ + C₂O₄ ^2–

Oxalic acid, H₂C₂O₄, is a diprotic acid with K₁ = 5 x 10^–2 and K₂ = 5 x 10^–5. Which of the following is equal to the equilibrium constant for the reaction represented above?

• 5 x 10^–2

• 5 x 10^–5

• 2.5 x 10^–6

• 5 x 10^–7

Tags

NGSS.HS-PS1-7

PCl₃(g) + Cl₂(g) ↔ PCl₅(g) + energy

Some PCl₃ and Cl₂ are mixed in a container at 200°C and the system reaches equilibrium according to the equation above. Which of the following causes an increase in the number of moles of PCl₅ present at equilibrium?

• Decreasing the volume of the container

• Raising the temperature

• Adding a mole of He gas at constant volume

• Raising the temperature and adding a mole of He gas at constant volume

Tags

NGSS.HS-PS1-5

4 HCl(g) + O₂(g) ↔ 2 Cl₂(g) + 2 H₂O(g)

Equal numbers of moles of HCl and O₂ in a closed system are allowed to reach equilibrium as represented by the equation above. Which of the following must be true at equilibrium?

• The [HCl] must be less than [Cl₂].

• The [O₂] must be greater than [HCl].

• The [Cl₂] must equal [H₂O].

• The [O₂] must be greater than [HCl] and [Cl₂] must equal [H₂O].

2 SO₂(g) + O₂(g) ↔ 2 SO₃(g) When 0.40 mole of SO₂ and 0.60 mole of O₂ are placed in an evacuated 1.00-liter flask, the reaction represented above occurs. After the reactants and the product reach equilibrium and the initial temperature is restored, the flask is found to contain 0.30 mole of SO₃. Based on these results, the expression for the equilibrium constant, Kc, of the reaction is

• 
• 
• 
• 

Tags

NGSS.HS-PS1-7

2 SO₃ (g) ↔ 2 SO₂ (g) + O₂ (g)

After the equilibrium represented above is established, some pure O₂ (g) is injected into the reaction vessel at constant temperature. After equilibrium is reestablished, which of the following has a lower value compared to its value at the original equilibrium?

• Keq for the reaction.

• The total pressure in the reaction vessel.

• The amount of SO₃ (g) in the reaction vessel.

• The amount of SO₂ (g) in the reaction vessel.

Tags

NGSS.HS-PS1-6