Le Chateliers Principle:

1
Le Chateliers Principle

• A change imposed on a system at equilibrium
  shifts the equilibrium position in the direction
  that reduces that change.

2
Factors that alter chemical equilibrium are
changes in

• Concentrations (reactant and/or product)
• Pressure/volume (for gases)
• temperature

3
1. Change in Concentration

• Equilibrium shifts to reduce added substance or
  produce the removed substance

4
2. Pressure/ volume Changes

• Increased P (decreased V) shifts equilibrium to
  side with fewest of gas molecules
• Less P shifts it to side with more molecules

5
Examples

• NO(g)O3(g) ? O2(g) NO2(g)
• 2NO(g)Br2(g) ? 2NOBr(g)

6
3. Temperature Change

• Heat is part of reaction see which side it is
  on.
• Exothermic rxns Keq decreases with rising T
• Endothermic rxns Keq increases with rising T

7
Problem

• 2SO2 (g) O2 (g) ? 2SO3 (g)

8
Problem

• NH4Cl(s) heat ? NH3(g) HCl(g)

9
Haber Process

• N2 (g) 3 H2 (g) ? 2NH3 (g) heat