Chemical Equilibria 06 Flashcards
definition of a reversible reaction
reversible reactions occur in both directions at the same time, where a mixture of reactants and products are obtained.
definition of dynamic equilibrium
when there’s a dynamic equilibrium, the rate of the forward reaction equals the rate of the backward reaction. It can only be achieved in a closed system.
le chatelier’s principle definition
states that when an system in equilibrium’s subjected to a change in conditions which disturbs the equilibrium, it will cause a shift in the POE so as to reduce that change.
effect of changes in partial pressure and concentration
Partial pressure is for gases only. The pressure of a gas in a system is directly proportional to the concentration of the gas.
The POE shifts such that the pressure of the reactant added is decreased
effect of changes in total pressure (for gases only)
pressure does not have an effect on solids or liquids. The POE will shift in the direction of the reactant that has less moles (eg 4 moles towards 2 moles) so as to decrease the pressure by favouring the production of fewer number of moles of gas.
effect of changes in temperature
when the t is increased, the POE will shift to favour the endothermic process to ABSORB THE ADDITIONAL HEAT. when the t is decreased, the POE will favour the exothermic reaction so as to GENERATE ADDITIONAL HEAT.
effect of a catalyst
IT DOES NOT AFFECT THE POE!!
it only shortens the time needed to obtain the FINAL equilibrium as it lowers the activation energy of the forward and backward reactions TO THE SAME EXTENT.
formula of Kc
[A]^a[B]^b / [C]^c[D]^d
cannot be used for SOLIDS only gas and aqueous can
what affects Kc?
only TEMPERATURE affects Kc value
