Phase Equilibria And Gibbs Free Energy

Question 1

What is formula for G/n regarding phase equilibrium(phases α and β)

Answer 1

G/n=μ(β)+(n(α)/n)*(μ(α)-μ(β))

Question 2

How do we determine which phase is stable in phase equilibrium

Answer 2

•μ(α)>μ(β)=>phase β is stable
•μ(β)>μ(α)=>phase α is stable
•μ(α)=μ(β)=>there is phase equilibrium

Question 3

How can internal energy be expressed in reversible transformation with only volume work and change in U is infinitesimal

Answer 3

Consider a closed system where dw=dw(vol)=-pdV
dq=TdS
•dU=dq+dw=TdS-pdV

Question 4

What is property of differential

Answer 4

d(fg)=fdg+gdf

Question 5

What is expression of G using property of differential

Answer 5

dG=Vdp-SdT
(G)’=V(p)’-S(T)’

Question 6

So what is infinitesimal change dμ equal if we take into account dU and dG

Answer 6

dμ=-SmdT+Vmdp

Question 7

What is dμ/dT equal at constant pressure

Answer 7

-Sm

Question 8

What is dμ/dp equal at constant temperature

Answer 8

Vm

Question 9

What is formula for μ(T,v) for ideal gases with change of pressure

Answer 9

μ(T,V)=μ⊝(T)+RTln(p/p⊝)

Question 10

What is formula for μ(T,v) for condensed phases with change of pressure

Answer 10

μ(T,p)=μ⊝(T)
dμ=Vm⊝dp

Question 11

What is formula for standard chemical potential from T-T0 with constant pressure

Answer 11

μ⊝(T)-μ⊝(T0)=-Sm(T-T0)