equil, Kc Flashcards
def: dynamic
the forward and backward reactions proceed at equal rates
def: equilibrium
the concentration of the reactants and products are constant
def: le chatelier’s principle
the position of equilibrium will shift to oppose change made to the system
how is dynamic equilibrium reached?
at the start of the reaction, forward reaction is fast and backward reaction is slow;
after start, backward reaction speeds up as the forward reaction slows;
the rate of the forward reaction becomes the same as the rate of the backward reaction.
what is the equilibrium position when there are more products than reactants?
equilibrium position is on the right
what is the equilibrium position when there are more reactants than products?
equilibrium position is on the left
pressure only affects reactions involving…
gases
(the more moles = the greater the pressure)
an increase in pressure will always move the equilibrium to the side with the ….. moles
fewest
a decrease in pressure will always move the equilibrium to the side with the … moles
most
if there is an equal number of moles, a change in pressure leads to ….
no effect
a decrease in volume of container , leads to an …. in pressure
increase
an increase in volume of container, leads to a …. in pressure
decrease
def: catalyst and how does it work
a substance that speeds up the rate of reaction without being used up;
provided an alternative reaction pathway with a lower activation energy
when a catalyst is added to a reversible reaction:
rate of both forward and backwards reaction increase equally by the same amount;
there is no change to the position of the equilibrium;
dynamic equilibrium is reached faster
an increase in temperature favours the …. direction
endothermic
a decrease in temperature favours the … direction
exothermic
when can dynamic equilibrium occur?
only occurs if the reversible reaction is carried out in a sealed container so no product can escape - closed system
what does a reversible arrow mean
a reversible reaction
if the concentration of a reactant is increased:
the equilibrium will shift to the right, to oppose the addition of [reactant],
so yield of [product] increases
if the concentration of a product is increased:
the equilibrium will shift to the left, to oppose the addition of [product]
so yield of [reactants] increase
if the concentration of a product is decreased:
the equilibrium will shift to the right,
to oppose the decrease in [products],
so yield of [product] increases
if the concentration of a reactant is decreased:
the equilibrium will shift to the left,
to oppose the decrease in [reactants],
so yield of [reactant] increases
exothermic reactions
releases heat energy,
temperature of surroundings increase,
enthalpy change is negative (minus delta H)
endothermic reactions
absorb heat energy,
temperature of surroundings decrease,
enthalpy change is positive (plus delta H)