Chemical Equilibria, Le Chateliers Princple Flashcards
What is a reversible reaction
The reactants turn into products and the products can be turned back into reactants
Define dynamic
When the forward and backward reactions proceed at equal rates
Define equilibrium:
When the concentration of reactants and products are constant
How is dynamic equilibrium reached ?
- at the start the forward reaction speeds up and the backward reaction slows down
- after the start the reverse reaction speeds up and the forward reaction slows down
- the rate of reaction for the forward reaction becomes the same as the backward reaction
What is a closed system
When dynamic equilibrium can only occur if the reversible reaction is carried out in a sealed container so that no products can escape.
True/false
It is often the amount of reactants to equal the amount of product
False it is very rare
what is Le Chatelier’s Principle:
the principle that the position of equilibrium will shift to oppose a change made to it
what are three factors that can affect equilibrium
- concentration
- pressure
- temperature
in a reaction: CO + H20 CO2 +H2
if concentration of CO is increased what will happen
equilibrium will shift to the right to oppose the increase in CO. so yield of CO2 and H2 increases.
in a reaction: CO + H20 CO2 +H2
what will happen if CO concentration is decreased
equilibrium will shift to the left to oppose the decrease in CO so yield of CO and H20 increases.
when the temperature of the following reaction is decreased, the equilibrium yield of product increases. is the forward reaction exothermic or endothermic?
3H2(g) + N2(g) —-> 2NH3(g)
forward reaction is exothermic as equilibrium shifts to the right so yield of NH3 (product) increases.
sulfur trioxide decomposes to form sulfur dioxide and oxygen at temperature T1. according to the equilibrium shown
2SO3(g) 2SO2(g) +O2(g) EC:196KJ/mol
the mixture was allowed to reach equilibrium at a different temperature T2, and yield of SO2 increased.
deduce which of T1 OR T2 is the lower temperature.
T2 is higher as the yield of SO2 increased and that is a product so had to be a forward reaction and is endothermic. so equilibrium shifts to the right to oppose the increase in temperature.
what happens when a catalyst is added to a reversible reaction:
- the rate of both the forward and backward reactions increases equally
- there is no change to the position of the equilibrium
- dynamic equilibrium is reached faster
