equilibrium Flashcards
why are solids not included when finding Kp
their pressure is constant
explain why the equilibrium constant would have no units
the units cancel
what measurement is used for Kp
partial pressure
what measurement is used for Kc
concentration
how do you calculate partial pressure
mole fraction x total pressure
explain one benefit to the environment of using catalysts in industry
reaction can occur at lower temperature so less fuel is used
concentration of catalyst is increased; state the effect on equilibrium position and rate of attainment of equilibrium
no effect on position of equilibrium; equilibrium is reached faster
how to write expressions for equilibrium constants
products / reactants
CH4 + H2O <=> CO + 3H2; pressure of equilibrium is increased; state and explain the effect on Kp
no effect because Kp only depends on temperature (same for all equilibrium constants)
how to write partial pressure of chemical ‘a’
P(a)
how to write mole fraction of chemical ‘a’
X(a)
suggest why industrial reactions never actually reach equilibrium
product is removed
what is dynamic equilibrium
rate of forward and backward reactions are equal; concentrations of reactants and products stay constant
forward reaction has an enthalpy change of -745 kJ/mol; state, with a reason, the effect of lowering temperature on the position of equilibrium
shifts to the right; exothermic in forward direction
2NO + 2CO <=> N2 + 2CO2; state, with a reason, the effect of increasing pressure on the position of equilibrium
shifts to the right; in direction of fewer molecules
CO + 2H2 <=> CH3OH; explain why increasing pressure increases the yield of methanol; give one disadvantage of increasing pressure
it is on the side with less molecules; more expensive equipment needed
explain, in terms of total ΔS(total) and ΔS(surroundings), why an exothermic equilibrium gives greater yield at lower temperature
ΔS(surroundings) becomes more positive (because reaction is exothermic for -ΔH/T); so ΔS(total) becomes more positive
how to increase an equilibrium’s atom economy without changing temp or pressure
remove product as it is formed; recycle unreacted reactants
