Equilibrium (AP Chem)

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-PS1-6

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-PS1-6

NGSS.HS-PS1-4

How many moles of NaF must be dissolved in 1.00 liter of a saturated solution of PbF₂ at 25 °C to reduce the [Pb²⁺] to 1 x 10^–6 molar? (Ksp of PbF₂ at 25 °C = 4.0 x 10^–8)

• 0.020 mole

• 0.040 mole

• 0.20 mole

• 0.40 mole

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

The solubility of CuI is 2 × 10^–6 molar. What is the solubility product constant, Ksp, for CuI?

• 1.4 × 10^–3

• 2 × 10^–6

• 4 × 10^–12

• 2 × 10^–12

Tags

NGSS.HS-PS1-7

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].

Tags

NGSS.HS-PS1-7