1.6 Equilibria Flashcards
what is the definition of dynamic equilibria
when forward and backward reactions occurs simultaneously
what are the two features of dynamic equilibria
- the forward and backward reaction occur at equal rates.
- the concentrations of reactants and products stay constant
what is a closed system
where no reactants or products can escape
what is Le Chatelier’s principle
if a system at equilibrium is disturbed, the equilibrium shifts to oppose the change
what is the effect of temperature on equilibrium
if temp increases the equilibrium will shift to oppose the change and move in the endothermic direction, to decrease the temp.
if temp decreases the equilibrium will shift to oppose the change and move in the exothermic direction, to increase the temp.
what is the effect of pressure on equilibrium
increasing pressure will cause the equilibrium to shift to the side with the fewest molecules to oppose the change, reducing the pressure
decreasing pressure will cause the equilibrium to shift to the side with the most molecules to oppose the change, increasing the pressure
*the position of equilibrium doesn’t change when there is an equal number of moles on both sides.
what is the effect of concentration on equilibrium
increasing the conc of the reactants causes equilibrium to shift to oppose the change and move to the right, favouring the forward direction decreasing the conc of the reactant. ( and vice versa)
what is the effect on catalysts on equilibrium
a catalyst has no effect on the position of equilibrium, but it will increase the rate at which equilibrium is achieved.
the haber process
N2 + 3H2 = 2NH3
T= 450c P= 200 - 1000 atm
iron catalyst
equation for the equilibrium constant
Kc = [C]^c [D]^d / [A]^a [B]^b
(the square bracket representing concentrations)
what is a homogeneous reaction
where all the reactants and products are the same physical state.
what is the heterogeneous reaction
where the reactants and products have different physical states.
what is the only condition which affects the value of Kc
temperature
what does the value of Kc suggest about the position of equilibrium
> 1 = shifts to the right
<1 = shifts to the left
what does the value of Kc suggest about the composition of the equilibrium mixture
small Kc = mixture is mostly reactants
large Kc = mixture is mostly products
how do we know if the reaction has gone to completion by looking at the Kc value
Kc value larger than X10^10, reaction has gone to completion
Kc value less than X10^-10, reaction isnt taking place
what effect does decreasing temp on an endothermic reaction have on Kc
Kc will decrease
what effect does increasing the temp in an endothermic reaction have on Kc
Kc will increase
what effect does decreasing temp in an exothermic reaction have on Kc
Kc will increase
what effect does increasing the temp in an exothermic reaction have on Kc
Kc will decrease
