Equilibria Flashcards
What is meant by the term ‘dynamic equilibrium’?
A reaction in a closed system, in which the concentrations remain the same.
State Le Chatelier’s principle.
If a system at equilibrium is disturbed, the equilibrium moves in the direction that tends to reduce the disturbance.
What would happen if the concentration of a reactant was increased in a reaction?
More products would be formed, position of equilibrium shifts to the right.
Given that there are more moles of gas on the right hand side of the reaction, state the outcome of an increase in pressure.
Less products would be formed, position of equilibrium shifts to the left.
Given that a reaction in equilibria is exothermic, state the outcome of an increase in temperature.
Less products would be formed, position of equilibrium shifts to the left.
What can be used in equilibria to speed up the reaction, without changing the position of equilibrium.
Catalyst.
How does a catalyst work?
They provide an alternative route to the reaction which has a lower activation energy.
What is the symbol equation for the reaction that forms ammonia in equilibrium?
N2(g) + 3H2 2NH3(g)
How do we acquire the reactants needed for the ammonia reaction?
Nitrogen comes from the air.
Hydrogen comes from water and natural gas.
What is ammonia used for?
Mostly used for fertilisers.
Also used for making nylon, explosives, drugs and dyes.
In equilibrium reactions, what do we visually see?
Nothing - the macroscopic properties remain the same, changes only occur at the microscopic level.
What catalyst is used for the reaction to produce ammonia and what size is it?
Iron. Pea-sized.
How often must the catalyst be replaced in the production of ammonia and why?
Every 5 years due to impurities.
What conditions are used in the production of ammonia?
20,000kPa.
670K.
What is the symbol equation for the formation of ethanol in equilibrium?
C2H4(g) + H2O(g) C2H5O (g)
What conditions are used in the production of ethanol?
6500kPa.
570K.
Why can the pressure not be too high in the production of ethanol? Not including safety, environmental or economical reasons.
This might cause the formation of polythene.
What catalyst is used in the formation of ethanol?
Phosphoric acid/ H3PO4 (absorbed on silica).
Why would an increase in the concentration of steam in this reaction cause a problem?
It would dilute the acid catalyst.
What is the symbol equation for the formation of methanol in equilibrium?
CO(g) + 2H2(g) CH3OH(g)
What conditions are used in the production of methanol?
10,000kPa.
500K.
What is the principal use of methanol?
Chemical feedstock - a starting material for making other chemicals.
In the production of ammonia, ethanol and methanol, a very low yield of product is achieved. How can a higher yield be achieved without changing the reaction conditions?
Recycle the unreacted reactants/ feed them back into the reactor.
In the production of ammonia, ethanol and methanol, why is a high temperature used despite the reaction being exothermic?
To speed up the process/ faster rate of reaction.
