Le Chatelier

Le Chatelier Principle:
Ref: pp450-456
When an llbm system is upset, the system responds in such a way as to oppose the change.

Ways to Upset llbm
-change the concentration (add/remove stuff)
   add - llbm shifts to the opposite side to try to 'use up' what was added
   remove - llbm shifts to same side to try to 'replace' what was removed
-change the temperature
  -it sometimes helpful to include the heat term as part of the equation [not deltaH notation], then think of 'heat' like any other substance
   exothermic:
    reactant -->  product + heat
    increase temp (like adding heat), reaction shifts to reactant side(reverse reaction requires heat)
    decreae temp (Like remoivng heat), reaction shifts to product side (forward reaction produces heat)
  endothermic - the opposite of exothermic
-change the pressure/volume
   increase volume (decr pressure) - llbm shifts to side with more moles of gas
        more moles of gas = more pressure, thus trying to increase pressure to be close to previous pressure
   decrease volume (incr pressure) - llbm shifts to side with fewer moles of gas
        fewer moles of gas = less pressure, thus trying to decrease pressure to be close to previous pressure

Variables that DO NOT affect llbm position
-addition of a catalyst - just reach llbm sooner
-addition of an inert gas (gas that does not react with any aspect of the llbm system) - interferes equally affects the probability of collision between both reactant and product particles

Hmwrk: p457(1,4,5,6)    p458(8)   p459(2*,3,5,6)  p460(10,12)  *just predict the shift, no sketch

Why did the chicken cross the road?  According to Le Chatelier: The chicken crossed the road because there were too many moles of chicken on the reactants side of the road equilibrium.