1.6 Equilibria & Kc Flashcards
How is dynamic equilibrium reached
- at start forward reaction is fast and backwards reaction is slow
- after start, forward reaction slows down and reverse reaction speeds up
- rate of forward reaction becomes same as rate of backward reaction
State Le Chatelier’s principle
If a change is made to a system in dynamic equilibrium, position of the equilibrium moves to counteract this change
What system can dynamic equilibrium occur
Can only occur in systems, where no substances can get in or out to affect the reaction
What happens to equilibriums if concentration of reactants increases
Equilibrium will shift to products, so yield of products increases
What happens to equilibrium if you increase pressure
Equilibrium shifts to the side with fewer moles
What values affect the value of Kc and what doesn’t
Not affected by contention change but affected by change in temperature
Give two features of a reaction at equilibrium, which is also the meaning of term dynamic equilibrium
- forward rate = backward rate
- concentrations of reactants and products remain or stay constant
Give meaning of term dynamic in dynamic equilibrium
Forward rate = backward rate
Let’s say methanol is on the right of the equilibrium, and equilibrium shifts to the right. Does the yield of methanol increase or decrease
Increase
A because equilibrium shifts to right to oppose increase in concentration
Think of equation PV=nRT. If volume of container increases pressure decreases (assuming everything else stays constant), Decrease in pressure leads to higher yield of side with more moles. Hence concentration of Oxygen is higher and has more moles
If Kc decreases, what does this mean for equilibrium
Equilibrium shifts to the left. Kc = conc of products / conc of reactants
So yield of reactants increase and yield of products decreases
Only do part c
Let’s say a colour change is dependent on an equilibrium, what could you say if equilibrium shifted to the right
More of the desired colour was produced, example of sun of colour is orange, say solution went more orange
A
Meaning of term catalyst and how it works
Meaning : speeds yo chemical reaction without being used up
How : lowers activation energy and provides alternate pathway
C
Explain in terms of behaviour of particles, why a high pressure is used
Rate of reaction increases
More particles closer together
More successful frequent collisions
Effect of increasing pressure on Kc
No effect
