Chemical Equilibrium Flashcards
(14 cards)
What is a reversible reaction?
Reversible reactions are reactions in which the products can react together to form the original reactants
What is dynamic equilibrium
Dynamic equilibrium is when the rate of the forward reaction is equal to the rate of the reverse reaction - at this point, the concentrations of the reactants and products remain constant
Outline Le Chatelier’s principle
When a system is subject to a change in conditions, the position of equilibrium will shift to lessen the effect of that change
How is Le Chatelier’s principle used in industry?
It can be used to alter the reaction conditions to maximise the yield of a desired product
What happens to the equilibrium position is temperature is increased?
If you increase the temp
- equilibrium will shift to favour the endothermic reaction
- as excess heat needs to be taken in from the system to lessen the effect of the increase
- this increases the yield of the endothermic products
What happens to the equilibrium position is temperature is decreased?
If you decrease the temp
- position of equilibrium will shift to favour the exothermic reaction
- as heat needs to be released to lesson the effect of the decrease
- this increases the yield of the exothermic products
What happens to the position of equilibrium if pressure is increased?
Increasing pressure favours side with fewer molecules of gas, as this helps to release the build up in pressure
What happens to the position of equilibrium if pressure is decreased?
Decreasing pressure favours the side with more moles of gas, as pressure has been lost
What happens to the position of equilibrium when concentration is increased?
Increasing conc of reactants will favour the forward reaction that produces the products as more molecules are available to react. This increases the yield of profucts
What happens to the position of equilibrium when concentration is decreased?
Decreasing conc of the reactants will favour the backwards reaction that reforms the reactants, increasing the yield of the reactants
What effect does adding a catalyst have on the equilibrium position?
Catalysts do not affect the equilibrium position as they increase the rate of the forwards and backwards reactions equally. They allow equilibrium to be reached faster but have no effect on the position of equilibrium
What are the optimum conditions for the Haber process?
High pressure as forward reaction produces fewer gas molecules
Low temp as forward reaction is exothermic
What is the equation for the Haber process?
N2 (g) + 3H2 (g) -> 2NH3 (g)
What does Kc indicate?
Kc indicates the position of equilibrium for a reaction at a certain temp
