Le Châtelier’s Principle - equilibrium position changed when outside force disturbs the system

• affected by concentration, temperature, pressure
• change in reactant/product concentration >> reaction shifts to use up the added substance
• lower volume, higher pressure >> reaction shifts to produce less moles of gas
• higher volume, lower pressure >> reaction shifts to produce more moles of gas
• higher temperature >> reaction shifts to use up extra energy (depends on whether reaction is exothermic/endothermic)
• catalysts - only changes how fast equilibrium is achieved, not characteristics of equilibrium itself

Describe the effect on CaCO3(s) >> CaO(s) + CO2(g) when:  

• pressure increased
  • shifts so that less gas is produced
  • shifts left
• volume increased
  • same as decreasing the pressure
  • shifts right to produce more gas
• adding CaCO3
  • no effect, it's a solid

For reaction PCl5(g) >> PCl3(g) + Cl2(g), K = 0.015 and DH = -375. What happens when Cl2 is removed?  

• disregard K or DH
  • they have nothing to do w/ the problem
• reaction shifts right to produce more Cl2

For endothermic equation N2(g) + O2(g) >> 2NO(g), K = 4.0 x 10-4. What happens when pressure is increased?  

• again, disregard K
• same amount of moles of gas on both sides of equation
• reaction doesn't shift to either side

For endothermic equation N2(g) + O2(g) >> 2NO(g), K = 4.0 x 10-4. What happens when temperatre is increased?  

• N2(g) + O2(g) + energy >> 2NO(g)
• adding temperature >> adding energy
• reaction shifts right to use up energy