6 equilibria Flashcards
what is a reversible reaction?
a reaction that can go forwards and backwards
when is equilibrium reached?
when there is a balance between the amount of products and reactants
when the concentration of each substance stays constant
why does equilibrium only occur in closed systems?
products can’t escape
what is le chateliers principle?
if a reaction at equilibrium changes in pressure, temperature or concentration, the position of equilibrium will move to minimise/counteract the change
if equilibrium shifts to the left do you make more products or reactants?
reactants
if equilibrium shifts to the right do you make more products or reactants?
products
which way would the equilibrium shift if the concentration of a reactant was increased?
right
which way will equilibrium shift if the concentration of a product is increased?
left
which way will equilibrium shift if pressure is increased?
to the side with the fewest moles/gas molecules
which way will equilibrium shift if pressure is decreased?
to the side with the most moles/gas molecules
which way will equilibrium shift if temperature is increased?
in the endothermic direction
which way will equilibrium shift if temperature is decreased?
in the exothermic direction
which way will equilibrium shift if a catalyst is added?
catalysts have no effect on equilibrium- it will speed up the rate of both reactions equally
what is the reversible reaction for ethanol?
ethene + water -> ethanol
H2C=CH2 + H2O -> CH3CH2OH
what are the conditions for making ethanol?
low temp (570K)
high pressure (65000kPa)
phosphoric acid catalyst (H3PO4)
what is a problem of ethanol production?
high pressure is expensive
what would be the calculation for Kc for
2A + B <-> 2C + D?
Kc = [C]2 x [D] / [A]2 x [B]
what do the square brackets mean in Kc calculations?
concentration of
how do you find moles?
mass/Mr / conc x vol
what does ICE box stand for?
initial moles
change in moles
equilibrium moles
how does change in temperature affect Kc?
if equilibrium shifts to right Kc will increase
if to left, Kc will decrease
how does change in concentration affect Kc?
no effect
what is a homogenous reaction?
a reaction where all reactants and products are in the same phase
