Chem thermo question.

[LoLCareerGoals]

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If such questions are not intended, sorry mods. But I am a bit puzzled here:

From Chemistry the Central Science Ed 10:


For blood plasma [K+] = 0.005M
For muscle-cell fluid [K+] = 0.15M
Two are separated by a membrane only K+s can pass. What is deltaG for moving 1 mol of K+ from blood to muscle-cell fluid at 310K?

deltaG = deltaGnot + RT*lnQ
So to find K:

[K+] ([email protected])<-> [K+] (cell [email protected])
Q = .15/0.005=30

deltaG = deltaGnot + 8.314*310*ln30

Answer is just whatever it would be if deltaGnot was zero.
Appendix has some non-zero values for deltaGo for Li+(aq), Na+(aq) so I assumed there would be something similar for K+. Am I missapplying a concept here?
Would appreciate it if you have some insight.

 

[karafox]

&#916;G°= -RTln(K_eq)
If &#916;G° = 0, then K_eq = 1, since ln(1) = 0.

At equilibrium, K_eq = 1, since [K+_blood] = [K+_muscle] (the questions states that K+ ions are permeable to both sides).

 

[LoLCareerGoals]

Isn't this an osmosis pressure setup? How do you know concentrations will be equal at equilibrium?
I am quoting the book chapter that introduced osmosis pressure:
"Osmosis stops when the column of a solution on the left becomes high enough to exert sufficient pressure at the membrane to counter the net movement of solvent. At this point the solution on the left has become more dilute, but there still exists a difference in concentrations between the two solutions."