Reversible reactions Flashcards
What is the forward reaction?
reactants–>products (the one that goes right)
What is the backward reaction?
Products–>reactants (the one that goes left)
What is the word equation for the reaction for ammonium chloride?
ammonium chloride ⇌ ammonia + hydrogen chloride
What is the symbol equation for the reaction for ammonium chloride?
NH4Cl (s) ⇌ NH3 (g) + HCl (g)
If a reaction is endothermic in one direction and exothermic in the other direction
the same amount of energy is transferred in both the forward and reverse reactions.
What is the equation for a reversible reaction?
A + B ⇌ C+D
Describe what equilibrium is
When a reversible reaction occurs in apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and reverse reactions occur at exactly the same rate.
What happens as the reactants react? And what will simultaneously happen to the products?
As the reactants react, their concentrations fall so the forward reaction will slow down. But as more products are made, their concentrations rise and the backward reaction will speed up
What will eventually happen?
After a while, the forward reaction will be going at exactly the same a rate as the backward one- the system is at equillibrium
What happens AT equillibrium?
both reactions are still happening but there’s no overall effect (dynamic equilibrium). This means, that the concentrations of reactants and products have reached a balance and wont change
What condition needs to be met for equilibrium to be reached?
Equilibrium is only reached if the reversible reaction takes place in a ‘closed system’
What is a closed system?
None of the reactants or products can escape and nothing else can get in.
What does it mean if the equilibrium lies to the right?
the concentration of products is greater than that of the reactants
What does it mean if the equilibrium lies to the left?
the concentration of the reactants if greater than that of the products
What factors does the position of equilibrium depend on?
. temp
.pressure (only when gases are involved)
. concentration
What is the word equation for the ammonium chloride?
ammonium chloride ⇌ ammonia + hydrogen chloride
What does heat mean for the equilibrium of that reaction?
Heating this reaction moves the equilibrium to the right (more ammonia and hydrogen chloride) and cooling it moves it to the left (more ammonium chloride)
What is the equation for the thermal decomposition of hydrated copper sulphate?
hydrated copper sulphate ⇌ anhydrous copper sulphate + water
What does anhydrous mean?
without water
If you heat blue hydrated copper(II) sulphate crystals, it drives the water off and leaves the white anhydrous copper(II) sulphate powder. This is endothermic.
If you then add a couple drops of water to the white powder you get the blue crystals back again (exothermic)
