Chemical Equilibrium, Le Chatelier's Principle And Kc Flashcards
Some reactions are reversible
What is a reversible reaction
How is energy transferred
A reversible reaction is when the products can react to form the original reactants
The same amount of energy is transferred in each direction
When can dynamic equilibrium be reached
When a reversible reaction is carried out in a closed system, it will eventually reach dynamic equilibrium
Give two features of a reaction at equilibrium
The rate of forward reaction is equal to the rate of backward reaction
The concentration of reactants and products remains constant under constant conditions
Equilibrium can be reached from…
Equilibrium can be reached from both directions
How can you change the conditions of a reaction in a closed system
Change the concentration of one of the reactants
Change the temperature of he entire reaction vessel
Change the pressure inside the vessel
What is Le Chatelier’s principle
If a factor affecting the position of the equilibrium is altered, the position of the equilibrium shifts to oppose the effect of change
H + Cl -> HCl
Changing an equilibrium
What happens if the concentration of H is increased
The equilibrium shifts to the right to oppose the change by increasing the concentration of the product
PCl -> PCl + Cl
Changing an equilibrium
What happens if the pressure is increased
The equilibrium shifts to the left as there are fewer moles of gas and this opposes the change as the pressure decreases
What happens to equilibrium if temperature is increased
The equilibrium will shift to the endothermic side to oppose the chnage as it reduces temperature by absorbing heat
What happens to the equilibrium if temperature is decreased
The equilibrium shifts to the exothermic side as it opposes the change by increasing temperature as it gives out heat
How do Catalysts affect equilibrium
It increases the rate of both the forward and backward reaction equally
Equilibrium is reached faster but Catalysts do not affect the position of equilibrium
State the effect of a Catalyst on time taken to reach equilibrium
Time taken decreases
State the effect of a Catalyst on the position of equilibrium
It does not affect the position of the equilibrium
What are the 3 important factors to look for in equilibrium reactions in industry
-Yield of product
-Rate of reaction
-Cost of maintaining reaction conditions
Is the forward reaction in the Haber process exothermic or endothermic
Exothermic
What product does Hydration of ethene form
Ethanol
Is the forward reaction in Hydration of ethene exothermic or endothermic
Exothermic
What are the conditions used in the Haber process
450°C
200 atmospheres
Iron Catalyst
Ammonia is liquefied and removed as it is formed
What are the conditions used in Hydration of ethene
300°C
60 atmospheres
Concentrated phosphoric acid Catalyst
Ethanol is liquefied and removed as it is formed
In Hydration of ethene and the Haber process, the forward reaction is exothermic, what conditions WOULD produce the largest yield
Low temperature
High pressure
What is the equation for the Haber process
N2 + 3H2 -> 2NH3
Why do you compromise when low temperatures are needed
High yield but rate of reaction is slow
Why compromise when high pressures are needed
Why specifically in the Hydration of ethene
Good yield but higher energy costs for pumps to produce the pressure and for equipment to withstand high pressures
High pressure leads to unwanted polymerisation of ethene to form poly(ethene)
How do Catalysts help industries
Speed up the rate of reaction without being used up so lower temperatures can be used so lower energy costs and there is no effect on the equilibrium
What does Kc mean
Equilibrium constant
K Samsung notes
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What unit is used in Kc
Mol dm-³
Does concentration affect Kc
No
If kc is >1, what is the mixture mainly made of
Products
If kc is <1, what is the mixture mainly made of
Reactants
Why does adding a Catalyst have no effect on Kc
The catalyst doesn’t appear in the expression
It has no effect on Kc but equilibrium is reached faster
Factors Kc Samsung notes
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