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27 terms

LC Chem 8 Chemical Equilibrium

chemistry
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Static
State of equilibrium where the entire system is stable and not moving.
Dynamic
State of equilibrium where the system is moving but the two opposing motions balance each other
Reversible reaction
A reaction which takes place both in the forward and backward directions
Chemical equilibrium
A state of dynamic balance where the rate of the forward reaction equals the rate of the reverse reaction.
Le Chatelier's Principle
If a stress is applied to a system at equilibrium, the system readjusts to relieve the stress applied.
Decreasing the concentration of products
Favours the forward reaction in order to replace the products removed
Decreasing the concentration of reactants
Favours the backward reaction in order to replace the reactants removed
Increasing the concentration of reactants
Favours the forward reaction in order to use up the extra reactants
Raising the temperature
Favours the endothermic reaction (the rise in temperature is counteracted by the absorption of heat)
Lowering the temperature
Favours the exothermic reaction (the fall in temperature is counteracted by the emission of heat)
Increasing the pressure
Favours the reaction in which there is a reduction in volume (towards the side with the smaller number of molecules)
Catalyst
Substance which will speed up the rate of reaction but it will not change the position of the equilibrium
Haber Process
Process used to manufacture Ammonia
Iron
Catalyst used in the Haber Process
Low (temperature)
Le Chatelier's principle predicts the yield of NH3 in the Haber Process is maximised by these conditions of temperature
High (pressure)
Le Chatelier's principle predicts the yield of NH3 in the Haber Process is maximised by these conditions of pressure
500 C
Actual temperature used in the Haber Process (as lower temp reduces the rate)
200 ATM
Actual pressure used in the Haber Process (as higher pressure presents a risk of explosion)
Contact Process
Process used in the manufacture of Sulfuric Acid
Vanadium pentoxide
Catalyst used in the Contact Process
Low (temperature)
Le Chatelier's principle predicts the yield of SO3 in the Contact Process is maximised by these conditions of temperature
High (pressure)
Le Chatelier's principle predicts the yield of SO3 in the Contact Process is maximised by these conditions of pressure
450 C
Actual temperature used in the Contact Process (as lower temp reduces the rate)
1 ATM
Actual pressure used in the Contact Process (as higher pressure presents a risk of explosion)
Kc
Equilibrium constant = [C]c[D]d / [A]a[B]b
Temperature
Effects the value of Kc (should always be stated with the Kc value)
Concentration (of reactants or products)
Does not affect the value of Kc (reaction will deal with the changes and return to the same equilibrium value)