Calculate the actual, physiological ΔG for the reaction: creatine phosphate + ADP → creatine + ATP at 37°C, as it occurs in the cytosol of neurons with creatine phosphate at 4.7 mM, creatine at 1.0 mM, ADP at 0.73 mM, and ATP at 2.6mM. Give your answer in kJ/mol to one decimal point.

-13.2 kJ/mol

Explanation:

Creatine Phosphate  +  H₂O ------>   Creatine + P₁ (ΔG° = -43 kJ/mol)

ADP                             +  Pi    ------->   ATP +  H₂O   (ΔG° =  +30.5 kJ/mol)    

Creatine Phosphate  + ADP  ------> Creatine  + ATP   (ΔG° = -12.5 kJ/mol)

Given that:

Creatine Phosphate = 4.7 mM

ADP = 0.73 mM

creatine = 1.0 mM

ATP = 2.6mM

Temperature (T) = 37°C = (37+273)K

Temperature (T) = 310 K

ΔG° = -12.5 kJ/mol = -12500 J/mol

Rate constant = 8.314

Then using the formula and substituting our values, we have :

ΔG = ΔG° + RT㏑

ΔG =  - 12500  + (8.314)(310)㏑

ΔG =  - 12500 + 2577.34 × ㏑ [ 0.7578]

ΔG =  - 12500 + 2577.34 ( -0.2773)

ΔG = - 13214.696 J/mol

ΔG = - 13.215 kJ/mol

ΔG = - 13.2 kJ/mol    ( to 1 decimal place)

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.