3.1.6 Chemical equilibria Flashcards
Give the two things that prove/happen when a reaction is at equilibrium
Forward and reverse reactions are occurring at the same rate
The concentration of reactants and products remain equal
If at equilibrium are the concentration of reactants and products the same
No
They can be but it’s not a requirement
The concentrations must be constant but not necessarily the same
What is a closed system
No substances (products or reactants) are added to the system or are lost from it
Nothing leaves or enters the system
Why is it called DYNAMIC equilibrium
Both forward and reverse reactions are occurring
Which side does equilibrium have to be approached from
Either
Products or reactants
If enthalpy change sign is positive then forward reaction is
Endothermic
If the enthalpy change sign is negative then the forward reaction is
Exothermic
Increase temperature in equilibrium favours
Endothermic direction
Decrease temperature at equilibrium favours
Exothermic direction
What effect do catalysts have on equilibrium
No effect on position
But decrease time taken to reach equilibrium because it increases rate of forward and reverse reaction by the same amount
What effect does increasing pressure have on equilibrium
Shifts to side with less molecules
What effect does decreasing pressure have on equilibrium
Shifts to side with more molecules
Pressure only effects equilibrium when….
All substances are gases
What happens if we increase concentration of one of the substances at equilibrium
It will shift to the opposite side
( to explain why kinda confusing look in book)
State le chateliers principle
If a reaction is at equilibrium is subjected to change in pressure, temperature or concentration the position of equilibrium will move to counteract the change
Equilibrium can only happen when…..
Only in homogeneous reactions
All in the same state
Expression for Kc
Products / reactants
What is acronym for finding Kc concentrations
I - initial MOLES
C - change in MOLES
E- MOLES at equilibrium
All substance in equilibrium has the ….. volume
Same
Effect of catalysts on Kc
None
Effect of concentration on Kc
None
Effect of temperature on Kc
Yes
Look in book for how and explanation
What do the measurements for Kc have to be in
Concentration
Why can percentage uncertainty be okay for some experiments
Temperature CHANGE etc is bigger than the uncertainty
What effect does the catalyst have on the equilibrium constant
None
What is the one thing that effects equilibrium constant
Temperature
What effect does catalysts have on the rate of the reverse reaction
Increases it
When doing ICE for equilibrium moles does big numbers matter
YES
If you remove the product as it forms does this increase the yield of the product
Yes
