CHM 2046C Module 10-Chapter 16 Sample Test

Part D: Equilibrium Constant, K & The Reaction Quotient, Q 10 points

Make three generalizations concerning the composition of equilibrium mixtures:

a)

b)

c)

Determining a reaction quotient is useful for two reasons, state the reasons:

a)

b)

Demonstrate the Usefulness of the reaction Quotient:

The brown gas nitrogen dioxide, NO₂, will exist in equilibrium with the colorless gas, N₂O₄, K = 170 at 298 K.

2 NO₂ (g) ß à N₂O₄ (g) K = 170

Suppose that, at a specific time, the concentration of NO₂ is 0.015M, the concentration of N₂O₄ is 0.025M.

a) Is the Quotient Q larger than, or smaller than, or equal to K?

b) If the system is not a equilibrium, in which direction will the reaction proceed to achieve equilibrium?

Picture Interpretation:

The Reaction A₂ + B₂ <====> 2 AB has an equilibrium constant K_c = 4. The following pictures represent reaction mixtures that contain A₂ molecules (red), B₂ molecules (blue) and AB molecules:

a) Which reaction mixtures is at equilibrium?

b) For the reaction mixtures that are not at equilibrium, will the net reaction go in the forward or the reverse direction to react equilibrium?

See McMurry Section 13.5 pages 508-511.Look at Worked Example 13.8 p510, then work Problem 13.9 p 511 Work Problems 13.62-13.79 for D, E, F

See pages Kotz 767-9. Work Problems #3-#6 page 789