Equilibria and Kc Flashcards
What is dynamic equilibrium? (2)
The concentrations of the reactants and products remain constant
The rate of the forward reaction = rate of the reverse reaction
How is a dynamic equilibrium reached? Use reaction rates in your answer (3)
At the start of the reaction the forward reaction is fast and the backward reaction is slow
The backward reaction then speeds up as the forward reaction slows down
The rate of the forward reaction becomes the same as the rate of the backward reaction
State a condition for a reaction in equilibrium (1)
Closed system
State Le Chatelier’s principle (1)
Position of equilibrium will shift to oppose a change made to it
A + B —> <— C + D
What happens to the position of equilibrium if the concentration of reactants is increased?
Equilibrium will shift to the right to oppose increase in concentration of the reactants
Yield of products will increase
A + B —> <— C + D
What happens to the position of equilibrium if the concentration of reactants is decreased?
Equilibrium will shift to the left to oppose decrease in concentration of reactants
Yield of reactants increases
3A + B —> <— C + D
What happens to the position of equilibrium if pressure is increased?
There are fewer moles on the right
Equilibrium will shift to the right to oppose the increase in pressure
So yield of products increases
If there are equal number of moles of products and reactants, what affect would changing the pressure have on the position of equilibrium?
No affect
If the forward reaction is exothermic and the temperature of the reaction is decreased, what would happen to the position of equilibrium?
Equilibrium will shift to the right to oppose decrease in temperature
Yield of products increases
If the forward reaction is exothermic and the temperature of the reaction is increased, what would happen to the position of equilibrium?
Equilibrium will shift to the left to oppose increase in temperature
Yield of reactants increases
What is a catalyst?
A substance that speeds up the rate of a chemical reaction by providing an alternative reaction pathway with a lower activation energy
What happens when a catalyst is added to a reversible reaction? (3)
The rate of both the forward and reverse reaction increases equally
There is no change to the position of equilibrium
Dynamic equilibrium is reached faster
The Haber process is a reversible reaction that is used to produce ammonia. Why are catalysts added to Haber process? (1)
To reduce the time taken to reach dynamic equilibrium
Why are compromise conditions necessary? (2)
Higher temperature increases rate
Lower pressure requires less expensive equipment
Why is a catalyst used in the Haber process? (2)
To increase the rate of reaction so more product is produced within the same time frame
Reduces the cost of the reaction as less fossil fuel is burned to generate heat energy
