Equilibrium - Quiz Review

Consider the following reaction:

H₂ (g) + Br₂ (g) ⇄ 2HBr (g) K=2.18 x 10⁶ at 730^oC

Starting with just 3.20 moles of HBr in a 12.0-L reaction vessel, calculate the concentrations the bromine gas at equilibrium.

U8.L3(Pt. B) - Problem #1

• 1.80 x 10^-4 M

• 0.133 M

• 2.67 M

• 0.267 M

Consider the following reaction at 1650^oC:

H₂ (g) + CO₂ (g) ⇄ H₂O (g) + CO (g) K=4.2

Initially, 0.80 mol H₂ and 0.80 mol of CO₂ are placed into a 5.0-L flask. Calculate the concentration of water and carbon dioxie in the reaction mixture at equilibrium.

U8.L3(Pt. B) - Problem #2

• 0.11 M

• 0.052 M

• 2.1 M

• 0.025 M

A mixture initially containing 0.392 M A (g) and 0.452 M B (g) is allowed to come to equilibrium at 300 K. The reaction is as follows:

3 A(g) + 2 B(g) ⇄ C(g) + D(g)

At equilibrium, [C] = 0.00128 M. What is the molarity of gas A at equilibrium?

U8.L3(Pt. C) - Problem #4

• 0.388 M

• 0.449 M

• 0.00384 M

• 0.00256 M

A mixture initially containing 0.392 M A (g) and 0.452 M B (g) is allowed to come to equilibrium at 300 K. The reaction is as follows:

3 A(g) + 2 B(g) ⇄ C(g) + D(g)

At equilibrium, [C] = 0.00128 M. What is the value of K_c? (NOTE: Must first calculate the equilibrium molarities or A, B, and D at equilibrium to solve.]

U8.L3(Pt. C) - Problem #4

• 1.39 x 10^-4

• 2.32 x 10^-3

• 0.00256

• 3.89 x 10^-4

For reaction 2A⇄ B. Use the equilibrium concentrations from the graph to determine what the K_eq will be.

• K = 3

• K = 0.066

• K = 15

• K = 0.56

Shown is a concentration vs. time plot for the gas phase reaction A ⇄ B. Write down the equilibrium constant expression ("mass action fraction"), and then use equilibrium concentrations from the plotted data to determine the numeric value for K.

• 0.40

• 3.7

• 2.5

• 0.60

Gaseous hydrogen bromide decomposes at elevated temperatures according to the following equation:

2HBr (g) ⇄ H₂ (g) + Br₂(g)

At a certain temperature a 2.00 L flask is initially filled only with 0.600 mol of HBr. What is the value of K_c at that temperature if the flask contains 0.104 mol of H₂ at equilibrium? (Note: You must also figure-out the HBr and Br₂ molarities at equilibrium.)

• 7.04 x 10^-2

• 4.40 x 10^-2

• 0.210

• 3.00 x 10^-2

N₂O₄(g) ⇄ 2 NO₂(g)

What is the law of mass action for this system.

• K_c = [NO₂]²/[N₂O₄]

• K_c = [N₂O₄]/[NO₂]²

• K_c = [N₂O₄]²/[NO₂]

• K_c = [NO₂]/[N₂O₄]²

Determine the value of K for the reaction:

2 N₂(g) + O₂(g) ⇄ 2 N₂O(g)

Equilibrium concentrations are:

[N₂] = 3.6 M, [O₂] = 4.1 M,

[N₂O] = 3.3 × 10^-18 M

• 2.0 × 10^-37

• 4.5 × 10¹⁸

• 5.0 × 10³⁶

• 2.2 × 10^-19

What is the law of mass action?

Fe₃O₄(s) + 4H₂(g) ⇄ 3Fe(s) + 4H₂O(g)

• [Fe]³[H₂O]⁴ / [Fe₃O₄][H₂]⁴

• [Fe₃O₄][H₂]⁴ / [Fe]³[H₂O]⁴

• [H₂O]⁴ / [H₂]⁴

• [Fe][H₂O] / [Fe₃O₄][H₂]