CHEMICAL EQUILIBRIUM
- Rate of formation of products is equal to the rate of decomposition of products (rate of
forward = rate of reverse)
- Dynamic equilibrium = both reactions are taking place even though there is no visible
change
- Can only be reached in closed system
Le Chatelier’s Principle (use collision theory to explain)
- Can only be established under conditions of concentration, temperature an pressure
APPLICATION OF PRINCIPLE
1. identify stress (according to LCP)
2. State reaction that is favoured by change in conditions
3. Effect the change has on system
- Use collision theory
pV=nRT
- p=pressure
- v= volume
- n= moles
- R= constant for gas (8.31)
- T= temperature
Factors that affect equilibrium
- Concentration: does not affect pure substances (solids and liquids)
- Temperature: depends on whether or not reaction is endothermic or exothermic
- Increasing temperature favours the endothermic reaction eg reduce temperature
to counteract the stress
- Decreasing temperature favours exothermic reaction eg increase temperature
- Pressure: only affects gas,increasing pressure favours reaction that produces fewer
particles
- Catalyst: increased rates of both reactions equally and does not affect equilibrium
position
Equilibrium constant Kc (measure of what is happening at equilibrium)
- Rate of formation of products is equal to the rate of decomposition of products (rate of
forward = rate of reverse)
- Dynamic equilibrium = both reactions are taking place even though there is no visible
change
- Can only be reached in closed system
Le Chatelier’s Principle (use collision theory to explain)
- Can only be established under conditions of concentration, temperature an pressure
APPLICATION OF PRINCIPLE
1. identify stress (according to LCP)
2. State reaction that is favoured by change in conditions
3. Effect the change has on system
- Use collision theory
pV=nRT
- p=pressure
- v= volume
- n= moles
- R= constant for gas (8.31)
- T= temperature
Factors that affect equilibrium
- Concentration: does not affect pure substances (solids and liquids)
- Temperature: depends on whether or not reaction is endothermic or exothermic
- Increasing temperature favours the endothermic reaction eg reduce temperature
to counteract the stress
- Decreasing temperature favours exothermic reaction eg increase temperature
- Pressure: only affects gas,increasing pressure favours reaction that produces fewer
particles
- Catalyst: increased rates of both reactions equally and does not affect equilibrium
position
Equilibrium constant Kc (measure of what is happening at equilibrium)
