chemical equilibria Flashcards
what is chemical potential (mu)
whar is the standard chemical potential
The Gibbs free energy (G) of 1 mole of the substance at a specified concentration
the Gibbs free energy of 1 mole of that substance at a concentration of 1 mol/dm3 and at std conditions
how can Gibbs free energy be calculated of a substance at any conc
how does chemical potential vary for different concentrations
at conc [A]
MUa = stdMUa + RTln[A]
[A] < 1 mol/dm3, ln[A]<0
MUa < stdMUa
[A]>1 , ln[A] > 0 MUa>stdMUa
show equation for deltaG
which equation is use for gases
deltaG = deltaH - deltaTS
MUa = stdMU i+ RTln(P i)
partial pressure is used
how to calculate contribution to total GFE of each component
when num moles is changed and everything else is constant how do you find change in G
Gi = ni x MUi
multiply chemical potential of each component by number of moles of that component
dG = MUi x dni
how to define reaction quotient (Q)
Q = [product]^mol prod / [reactant]^mol reactant
can be expanded for multiple products and reactants
at equilibrium, Q will equal eq constant K
what is deltaG for a reaction not in equilibrium and a reaction in equilibrium
not in equilibrium: deltaG is the difference in gibbs energy between reactants and products leading to
deltaG=stddeltaG + RTln(Q)
equilibrium: chemical potential of products and reactants are equal so cancel
deltaG = 0 and Q=K
0 = stddetlaG + RTln(K)
position of equilibrium depends on std Gibbs free energy change going from reactants to products
how does K link to equilibrium position and std deltaG
K>1 position of equilibrium lies towards products and deltaG is negative
K<1 position of equilibrium lies to reactants and deltaG is positive
Show the temperature dependence of std deltaG
deltaG = -RT ln(K) deltaG = stddeltaH -T(delta_stdS)
ln(K) = -(deltaH/RT) + deltaS/R
plot ln(K) against 1/T assuming deltaH and deltaS don't vary with temp
what is the relationship between rate constants and equilibrium constant
K is ratio of rate constant of forward and reverse reaction
how is K dependent on temperature
K = e^ (std_deltaG / RT)
