10.4 Dynamic equilibrum and le Chatliers principle Flashcards
(22 cards)
What is a reversible reaction?
A reaction that takes place in both forward and backwards direction
How are reversible reactions represented?
⇌
Draw a graph representing representing a reversible reaction, explain its features
-Forward reaction, initially reactants are used up quickly but then slow as their concentration drops
-Backward reaction, initially reactants are reformed slowly, but then speed up as concentration of products increases
-When equilibrium is reached, the rate of the forwards reaction is equal to the rate of the backwards reaction, this is dynamic equilibrium and the concentration of each substance will remain constant
Where does dynamic equilibrium occur?
In closed systems
What are the features of a dynamic equilibrium?
-The rate of the forward reaction is equal to the rate of the backward reaction
-The concentrations of the products do not change
-The system must be closed, isolated from its surrounding so temperature, pressure, concentrations are unaffected by outside influences
What does le Chateliers principle state?
When a system in equilibrium is subject to external change (in temperature, pressure, or concentration), the system readjusts itself to miniseries the effect of that change
What happens if the position of equilibrium shifts left?
More reactants are made
What happens if the position of equilibrium shifts right?
More products are made
When changing concentration occurring to le Chateliers principle what needs to be present for it to work?
Only works in homogeneous equilibria, where reactants and products are in the same state
If we increase the concentration of H2 what happens to the equilibrium?
3H2 + N2 ⇌ 2NH3
Equilibrium will say right, to use up H2 and reduce its concentration, more NH3 will be produced
If we decrease the concentration of NH3 what happens to the equilibrium?
3H2 + N2 ⇌ 2NH3
Equilibrium will shift right, the increase the concentration of NH3
If we increase the concentration of NH3 what happens to the equilibrium?
3H2 + N2 ⇌ 2NH3
Equilibrium will shift left, to use up NH3 and reduce its concentration, more H2, N2 will be produced
If we decrease the concentration of H2 what happens to the equilibrium?
3H2 + N2 ⇌ 2NH3
Equilibrium will shift left to increase the concentration of H2 and N2
What is the effect of concentration on the position of equilibrium?
What happens if we increase the pressure in a dynamic equilibrium?
The equilibrium will shift to the side with the fewest number of gas particles, thus reducing pressure
What happens if we decrease the pressure in a dynamic equilibrium?
Position of equilibrium will shift towards the side with the most gaseous molecules, this will increase the pressure
What happens if we increase the temperature in a dynamic equilibrium
Equilibrium position will shift in the endothermic direction, this will reduce the temperature
What happens if we decrease the temperature in a dynamic equilibrium
Equilibrium position will shift in the exothermic direction, this will increase the temperature
What is the effect of a catalyst on the position of equilibrium?
-No effect, it will speed up the rate of the forward and backward reaction equally, and it will increase the rate at which equilibrium is reached but have no effect on yield
What is the symbol for an exothermic reaction?
negative ΔH
What is the problem with using high pressures?
Expensive, safety risk
What is the problem with using low temperatures?
Slow reaction rate
