physical chem; equilibrium constant Kp for homogeneous systems Flashcards
define the term total pressure
the total pressure in a reaction is the sum of all pressures of the individual gases (partial pressure)
how are partial pressures of gases calculated?
by using mole fractions
define the term mole fraction
it’s the proportion (fraction) of a gas in a gas mixture
how is the mole fraction of a gas calculated?
mole fraction of a gas = no.of moles of a gas / total no.of of mole of gas in the mixture
how is partial pressure calculated?
partial pressure = mole fraction of gas x total pressure in mixture
what can we calculate by using partial pressure values?
gas equilibrium constant - Kp
what is the Kp expression?
Kp = (p) (p) / (p) (p)
state the factors that affect Kp
- temperature
- pressure
- catalysts
explain the effect of temp on Kp
Kp is only valid for one temp
changing the temp = changes equilibrium pressures so Kp will also change
state the effects of temp change on Kp
if temp change causes equilibrium to shift right: Kp increases
if temp change causes equilibrium to shift left: Kp decreases
state the effects of increasing/decreasing temp on the equilibrium & Kp
increase temp: equilibrium shifts in endo direction - Kp decreases
decrease temp: equilibrium shifts in exo direction - Kp increases
state the effect of partial pressure values on Kp
product partial pressure increases = Kp rises
reactant partial pressure increases = Kp drops
state the effects of pressure on Kp
the value of Kp is unaffected by any changes in pressure
state the effect of catalysts of Kp
adding a catalyst does not affect the value of Kp as it speeds up both the forward & backwards reaction - it only speeds up the rate at which equilibrium is established
