equilibria and compromise conditions

what is a dynamic equilbrium?

a system where:

• concs of reactants and products remain constant

• forward and backward reactions are proceeding at equal rates in a closed system

  

state Le Chatelier’s Principle:

if a factor is changed which affects a system at equilibrium, the PoE will move in a direction so as to oppose the change

what happens when we increase the concentration of a reactant?

• PoE shifts to products to counteract reactant conc increase

• increasing product yield

what happens when we decrease the concentration of a reactant?

• PoE shifts to reactants to counteract the decrease in reactant concentration

• increases yield of reactants

what happens when we increase the pressure of a system?

• PoE shifts to the side w/ fewer gaseous moles to counteract the change by reducing the pressure again

• increasing the yield of the side w/ fewer gaseous moles

what happens when we decrease the pressure of a system?

• PoE shifts to the side w/ more gaseous moles to counteract the change by increasing the pressure again

• this increases the yield of the side w/ more gaseous moles

what happens when we increase the temperature of a system?

• PoE shifts in the direction of the endothermic reaction to oppose the increase in temperature and decrease the temperature again

• increases yield of the side of the endothermic reaction

what happens when we decrease the temperature of a system?

• PoE shifts in the direction of the exothermic reaction to counteract the decrease in temperature by increasing the temperature again

• increases yield of the side of the exothermic reaction

is the ΔH of an exothermic reaction > or < 0?

< 0

is the ΔH of an endothermic reaction > or < 0?

> 0

what effect would a catalyst have on the PoE? why?

no effect - increases rate of forward and backward reactions to same extent

what are the drawbacks of using a high temperature/pressure?

high equipment and energy costs