Journal Entry:

2X(g) ↔3Y(g) + Z(g)  ΔH_{forward rxn} >0

The molar equilibrium concentrations for the reaction mixture represented above at 298 K are [X] = 4.0M, [Y] = 5.0M, and [Z] =2.0M. What is the value of the equilibrium constant, Keq, for the reaction at 298K?
(A) 0.06
(B) 2.5
(C) 16
(D) 63

Learning Intentions

• We will learn how to use ICE to determine variables in the equilibrium expression.

• We will learn Le Chatelier's principle and how reaction respond to disturbance to equation in equilibrium.

• We will learn how the equilibrium constant (K) and reaction quotient (Q) are related to change in free energy (ΔG).

• We will learn how to make calculations using the ΔG°= -RT ln K and ΔG = ΔG°+ RT ln Q equations.

Closing Task:

You can determine the effect of a disturbance on a reaction in equilibrium using Q and  Le Chatelier's principle.

Content Standards being covered:

Systems at equilibrium respond to disturbances by partially countering the effect of the disturbance (Le Chatelier's principle). (E.K. 6.B.1)

A disturbance to a system at equilibrium causes Q to differ from K, thereby taking the system out of the original equilibrium state. The system responds by bringing Q back into agreement with K, thereby establishing a new equilibrium state. (E.K. 6.B.2)

When the difference in Gibbs free energy between reactants and products (ΔGº) is much larger that the thermal energy (RT), the equilibrium constant is either vary small (for ΔGº>0) or very large (for ΔGº <0). When ΔGº is comparable to the thermal energy (RT), the equilibrium constant in near 1. (E.K. 6.D.1)