Equilibria Flashcards
Describe the equation for Kc
For reaction:
aA +bB –>cC +dD
Kc = [C]c[D]d / [A]a[B]b
Describe what is meant by a homogenous equilibrium
An equilibrium in which all the species making p the reactants and products have the same physical state
How does increased pressure affect equilibrium?
Shifts equilibrium in favour of reaction with fewer moles of gas.
How does increased concentration of a reactant affect equilibrium?
Opposes change so shifts equilibrium in favour of other reactants.
Define Le Chatlier’s principle
If a constraint (such as a change in pressure, temperature, or concentration of a reactant) is applied to a system in equilibrium, the equilibrium will shift so as to tend to counteract the effect of the constraint.
How does temperature affect Kc
n exothermic reactions, an increase in temperature decreases the equilibrium constant, K, whereas, in endothermic reactions, an increase in temperature increases the K value.
Why would a compromise on temperature and pressure be used?
Increased temp and pressure boost reaction rate, however, requires energy to do so.
Energy is expensive so compromise is necessary.
Effect catalyst has on equilibrium
No effect
Define dynamic equilibrium
In a closed system
The rate of the forward reaction is equal to the backward reaction.
Define a closed system
A closed system is a system that is isolated from its surroundings, so temperature, pressure and concentrations of reactants and products are unaffected by outside influences.
Define heterogeneous equilibrium
Am equilibrium in which the species making up the reactants and products have different physical states.
Describe the equation for Kp
Kp = partial pressure of products / partial pressure of reactants
How to derive partial pressure
Partial pressure = molar fraction * total pressure
How does temperature affect Kp
Same as Kc
If the forward reaction is exothermic then if a temperature increase decreases the Kp
If the forward reaction is endothermic then if the temperature is increased the Kp increases
