3.1.6 Chemical equilibria, Le Chatelier’s principle and Kc Flashcards
In a reversible reaction at equilibrium:
- Forward and reverse reactions proceed at equal rates
- The concentrations of reactants and products remain constant
Le Chatelier’s principle
If a change is made to a system in dynamic equilibrium, the position of the equilibrium moves to counteract this change
What is a homogenous reaction
A reaction in which all reactants and products are the same state
Catalyst effect on equilibrium
NO EFFECT
Effect of an increase in temperature on equilibrium
Equilibrium shifts to favour endothermic reaction
To counteract change in temperature
Effect of an decrease in temperature on equilibrium
Equilibrium shifts to favour exothermic reaction
To counteract change in temperature
Effect of increased pressure on equilibrium
Equilibrium shifts to side with fewest moles of molecules
To counteract change in pressure
Effect of decreased pressure on equilibrium
Equilibrium shifts to side with most moles of molecules
To counteract change in pressure
Effect of increased concentration of reactant on equilibrium
Equilibrium shifts to product side of reaction to use up the increased concentration of reactant
Effect of decreased concentration of reactant on equilibrium
Equilibrium shifts to reaction side to produce more reactants,
to counteract change in concentration
Why is a compromise temperature and pressure used in reversible reactions in industry
Higher temp - Increases yield (more kinetic energy)
Lower temp - Cheaper, Safer, (Reaction may be exothermic)
Higher pressure - Increased rate of reaction
Lower pressure - safer
What type of reaction is Kc used for
Reversible reactions
Equation for Kc (aA + bB –> cC + dD)
[C]^c [D]^d / [A]^a [B]^b
Does a catalyst effect Kc value
No, as forward and backward reaction are increased at the same rate
Does a change in concentration effect Kc value
No, this is because by increasing concentration of reactants, you decrease the concentration of products.
What is the only factor that effects Kc
Temperature
