Question

This is from my biochem I class.. A reaction A + B --> C + D has deltaG^o' = 8 KJ/mole In the cell however, under steady state conditions we find
[A] = 2 mM, [B] = 2 mM, [C] = 10 microM & [D] = 40 microM
Find delta G' in KJ/mole

Answer 1

what does deltaG^o' mean?

Answer 2

\[DeltaG'^{o}\] is the biochemical standarad free-energy change
Where \[DeltaG ^{o}=DeltaG'^{o}+RT \ln (Keq)\]

Answer 3

ok now i get it i didnt get that G^0 but ok, if its steady state do you mean in equilibrium cause in equilibrium delta G = 0

Answer 4

id say you calculate Keq = [C][D]/[A][B] and then delta G if you know the temperature

Answer 5

deltaG^'0 is the gibbs free energy or reaction potencial at cell conditions, PH=7 T=36-37 C and G^0 its at STP
so it would be delta G^0=8+8.314(gas constant)*25+273.15(Kelvin)*(A*B/C*D)

Answer 6

So I'm working on problem 8

Answer 7

just make sure the molarity units are consistent

Answer 8

oh...I think I was not considering cell conditions

Answer 9

;D

Answer 10

i got 30,8 kJ/mol

Answer 11

ok so I guess it's just my math, but I'm getting a very different answer than the multiple choices

Answer 12

dont forget that 8 kJ/mol is 8000 J/mol so you add to that value you get from the rest of the equation

Answer 13

I have that the answer is suppose to be -14.8, choice c

Answer 14

seems legit, negative gibbs energy means that the reaction happends by it self without need of applying energy

Answer 15

let me try again:
i get that Keq = 1*10^-4 -> lnKeq = 9,21
T = 298 K
and R = 8,314
so i dont see how its negative and only if its negative you can get -14,8!
now only way i see is that you make assumption that its negative cause reaction is moved towards products...

Answer 16

i really dont have a clue how it can be negative sorry...

Answer 17

I think I might have gotten it. Using wolfram I get that the [A][B]/[C][D] portion = 1e-4 , and going by that you get -14.8 KJ. However, I still don't think I could get this by hand and a simple calculator

Answer 18

I didnt calculate it, if ur saying that the answer is -14.8 then it must be. but i agree with Kryten i dont see how its gonna be negative

Answer 19

I think my professor is just trying to make sure that we know the formula