Equilibrium Flashcards
What is dynamic equilibrium?
Rate of forward reaction equals rate of backwards reaction.
What does it mean when equilibrium lies to the left?
Little product is formed
What does it mean when equilibrium lies to the right?
Little reactant remains
What happens when concentration temperature or pressure is adjusted
The system moves the position of equilibrium in order to adjust to the change and return it to dynamic equilibrium
Concentration
•Reactants - Increase / decrease
•Products - Increase / Decrease
Reactants -
Increase - equilibrium moves to the right
Decrease - equilibrium moves to the left
Products -
Increase - equilibrium moves to the left
Decrease - equilibrium moves to the right
Temperature •Forwards reaction ENDOthermic (△H +ve) -Increase / -Decrease Forwards reaction EXOthermic (△H-ve) -Increase / -Decrease
Forwards reaction ENDOthermic (△H+ve)
Increase - Position of equilibrium to the right (take in heat to adjust increase)
Decrease - Position of equilibrium to the left (put out heat to adjust decrease)
Forward reaction EXOthermic (△H-ve)
Increase - Position of equilibrium to the left (backwards reaction endothermic so moves to the left to take in heat to adjust change)
Decrease - Position of equilibrium to the right (Does more of the exothermic reaction to give out heat as the temperature was decreased)
Pressure - only applied when all are gases •If reactants have fewer gas moles -Increase / -Decrease If products have fewer gas moles -Increase / -Decrease
If REACTANTS have fewer gas moles
Increase - Position of equilibrium moves to the left
Decrease - Position of equilibrium moves to the right
If PRODUCTS have fewer gas moles
Increase - Position of equilibrium moves to the right
Decrease - Moves position of equilibrium to the left
Does a catalyst affect the position of equilibrium?
No, it just allows equilibrium to be obtained more quickly.
For the reaction aA + bB ⇌ cC + dD, what is Kc
Kc = [C]^c[D]^d
—————-
[A]^a[B]^b
In other words products over reactants
What does the square brackets mean?
It is in concentration with units moldm^-3
What are the units of Kc and how do you work it out?
(moldm^-3) to the power of c+d divided by (moldm^-3) to the power of a+b
What does a high and low Kc tell us?
High - Equilibrium to the right
Low - Equilibrium to the left
What is the only thing that affects Kc?
Temperature
When the forward reaction is exothermic what happens when you increase temperature?
Position of equilibrium moves to the left hand side in the direction of the endothermic reaction, Kc is lower
When the forward reaction is endothermic what happens when you increase temperature?
Position of equilibrium moves to right hand side in the direction of the endothermic reaction, Kc is greater
