Reversible reactions and dynamic equilibrium (6.2) (M) Flashcards
What is a reversible reaction?
Reaction in which the products of the reaction can react to produce the original reactants
under certain conditions
How can a reversible reaction be represented?
A double-headed arrow (⇌)
How can you change the direction of reversible reactions
By changing the conditions.
How do the directions of a reversible reaction apply to exothermic and endothermic conditions?
If a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction
If a reversible reaction is exothermic and endothermic, how does energy in each reaction compare?
The same amount of energy is transferred in both the forwards and reverse reaction
In the exothermic and endothermic directions, the (…) amount of energy is transferred each way
same
Why might there be a loss in mass after a reaction in a reversible reaction?
Not all of reactant will react in a reversible reaction because the reaction does not go to completion
What is a closed system?
Chemical reaction that happens in apparatus which prevents the escape of reactants and products
When is equilibrium reached?
When the forward and reverse reactions occur at exactly the same rate
The relative amounts of all the reactants and products at equilibrium depend on what?
The conditions of the reaction
The effects of changing conditions on a system at equilibrium can be predicted using what?
Le Chatelier’s principle
What is Le Chatelier’s principle?
If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change
What happens if the concentration of one of the reactants or products is changed in equilibrium?
the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again
What happens in equilibrium If the concentration of a reactant is increased?
more products will be formed until equilibrium is reached again
(less reactants formed than products)
What will happen in equilibrium if the concentration of a product is decreased?
more reactants will react until equilibrium is reached again
2 things
What if the temperature of a system at equilibrium is increased?
- the relative amount of products at equilibrium increases for an endothermic reaction (increase at endo)
- the relative amount of products at equilibrium decreases for an exothermic reaction (decrease at exo)
2 things
What happens if the temperature of a system at equilibrium is decreased?
- the relative amount of products at equilibrium decreases for an endothermic reaction
- the relative amount of products at equilibrium increases for an exothermic reaction
For gaseous reaction at equilibrium, what does an increase in pressure cause?
the equilibrium position to shift towards the side with the smaller number of molecules as shown by the symbol equation for that reaction
(if side with smaller number of molecules are the products, the reactants to products symbol will be bigger)
For gaseous reactions at equilibrium, what does a decrease in pressure cause?
causes the equilibrium position to shift towards the side with the larger number of molecules as shown by the symbol equation for that reaction
(if side with smaller number of molecules are the products, the products to reactants symbol will be bigger)
What is the effect of a catalyst on equilibrium yield? Why?
no effect/change
because a catalyst increases the rate of the forward
and reverse reactions equally
Why might a change in pressure not affect the equilibrium mixture?
there may be no gases present
so no change in equilibrium position
