7. Energy, Rate and Equilibrium

Consider the reaction below:

CH₄ (g)  +  F₂ (g)  ⇌  CF₄ (g)  + HF (g)   H = + 38.1 KJ/mol

The following changes will shift the equilibrium to the left except one. Which one would not cause a shift to the left?

The following data was collected for the following reaction at equilibrium 

2 A (g) + 3 B (g)  ⇌ C (g)     

At 25 ^oC K is 5.2 x 10^-4 and at 50 ^oC K is 1.7 x 10^-7. Which of the following statements is true?

a) The reaction is exothermic.

b) The reaction is endothermic.

c) The enthalpy change, ΔH, is equal to zero.

d) Not enough information is given. 

Which direction will the following reaction (in a 10.0 L flask) proceed if a catalyst is added to the system? 

CaCO₃ (s)  ⇌ CaO (s) + CO₂ (g)            K_p = 3.2 x 10^-28

Consider the following gas reaction of A₂ ( shaded spheres) and B₂ ( unshaded spheres)

A₂ (g)  +  B₂ (g)  ⇌  2 AB (g) 

Which container proceeds more to completion? 

Is the yield of SO₃ at equilibrium favored by a higher or lower pressure? By a higher or lower temperature?

2 SO₂(g) + O₂ ⇌ 2 SO₃(g) ∆H = -47 kcal/mol

What effect do the listed changes have on the position of the equilibrium in the reaction of carbon with hydrogen?

C(s) + 2 H₂(g) ⇌ CH₄(g) ∆H = -18 kcal/mol (-75kJ/mol)

a. Increasing temperature

What effect do the listed changes have on the position of the equilibrium in the reaction of carbon with hydrogen?

C(s) + 2 H₂(g) ⇌ CH₄(g) ∆H = -18 kcal/mol (-75kJ/mol)

b. Increasing pressure by decreasing volume

What effect do the listed changes have on the position of the equilibrium in the reaction of carbon with hydrogen?

C(s) + 2 H₂(g) ⇌ CH₄(g) ∆H = -18 kcal/mol (-75kJ/mol)

c. Allowing CH₄ to escape continuously from the reaction vessel

Why do catalysts not alter the amounts of reactants and products present at equilibrium?

When the following equilibria are disturbed by increasing the pressure, does the concentration of reaction products increase, decrease, or remain the same?

a. 2 CO₂(g) ⇌ 2 CO(g) + O₂(g)

For the following equilibria, use Le Châtelier's principle to predict the direction of the reaction when the pressure is increased by decreasing the volume of the equilibrium mixture.

a. C(s) + H₂O(g) ⇌ CO(g) + H₂(g)

The reaction CO(g) + H₂O(g) ⇌ CO₂(g) + H₂(g) has ∆H = -9.8 kcal/mol (-41 kJ/mol). Does the amount of H₂ in an equilibrium mixture increase or decrease when the temperature is decreased?

The reaction H₂(g) + I₂(g) ⇌ 2 HI(g) has ∆H = -2.2 kcal/mol (-9.2 kJ/mol). Will the equilibrium concentration of HI increase or decrease when

c. A catalyst is added?

The reaction H₂(g) + I₂(g) ⇌ 2 HI(g) has ∆H = -2.2 kcal/mol (-9.2 kJ/mol). Will the equilibrium concentration of HI increase or decrease when

b. H2 is removed?

The reaction Fe³⁺(aq) + Cl^-(aq) ⇌ FeCl²⁺(aq) is endothermic. How will the equilibrium concentration of FeCl²⁺ change when

b. Cl^- is precipitated by addition of AgNO₃?