Unit 3 Part 3 - equilibrium Flashcards
what is equilibrium?
a balance point reached in a reversible reaction if the conditions are not altered
what happens at equilibrium?
the reactants change into products at exactly the same rate which the products change back into reactants
what happens to the concentration of products and reactants at equilibrium?
they remain constant but not equal (this can only happen in a closed system)
what is meant by the position of equilibrium?
the extent to which the reaction has taken place
what, on a graph, indicates that the reaction has reached equilibrium?
the curve leveling out
how can the position of equilibrium be altered?
when the reaction conditions are changed if an equilibrium has been established
how will an increase in products affect equilibrium?
shifts to the right
how will an increase in reactants affect equilibrium?
shifts to the left
what is la chatelier’s principle?
if a system at equilibrium is subject to a change, the position of equilibrium will move to oppose the change
how will increasing temp affect a reaction?
favours the endothermic reaction
how will decreasing temp affect a reaction?
favours the exothermic reaction
what is pressure a result of?
gas molecules bombarding the walls of the vessel in which the gas is contained
the …… the number of moles in a given volume, the …… the pressure
greater
how does increasing pressure affect the position of equilibrium?
position of equilibrium moves to the side with less moles of gas to decrease the pressure
how does decreasing pressure affect the position of equilibrium?
position of equilibrium moves to the side with more moles of gas to increase the pressure
give two rules about pressure in regards to the position of equilibrium?
pressure only affects the equilibrium of a system that involves gases + a pressure change will alter equilibrium only if there are different numbers of moles of gases on each side
describe the effect on the equilibrium of adding a catalyst
rates of both the forward and backward reaction will be increase + a decrease in activation energy, so a catalyst does not alter the position of equilibrium but speeds up the rate at which equilibrium is attained
how can the yield of ammonia be increased in the Haber process?
reaction conditions can be altered to increase the rate of the forward reaction to increase the yield of ammonia
how do changes in concentration contribute to increasing the yield of ammonia?
- ammonia gas is cooled and liquid ammonia is piped off in a condenser; constantyl removing the ammonia gas decreases the rate of the backward reaction
- unreacted hydrogen and nitrogen are recycled; the increase in the concentration of the reactant gases increases the rate of the forward reaction
how do changes in pressure contribute to increasing the yield of ammonia?
increasing pressure increases the rate of the forward reaction
the equilibrium shifts to the right because there are fewer moles of gas on the right - more ammonia would be produced
how do changes in temp contribute to increasing the yield of ammonia?
the reaction is exothermic so a drop in temp would cause the reaction to shift to the right; more ammonia would be produced
describe the effect of the catalyst used in the Haber process
iron catalyst
does not affect the position of equilibrium but allows the process to be carried out more efficiently at a lower temp
Maximum yield of ammonia in the Haber Process requires ………… pressure and ……….. temperature. The process is made cost-effective using ………….atmospheres, ……………°C and a……….. , giving about ……………… % yield. The ammonia produced is ……………….out and the unreacted gases are ……………
high, low, 200, 400, catalyst, 15, condensed, recycled
