what is the actual free energy chang?

If the isomerization reaction in the glycolytic pathway catalyzed by phosphoglucoisomerase:

glucose 6-phosphate --> fructose 6-phosphate

has a standard free energy change of +0.4 kcal/mol at 25˚C,

then [1] what is the actual free energy change (in kcal/mole) at 25˚C when:

the concentration of glucose-6-phosphate is 20 microMolar (20 x 10-6 M) and

the concentration of fructose 6-phosphate is 5 microMolar (5 x 10-6 M)?

[2] Is the reaction favorable or not?

Show how you arrived at your answers if you want to receive partial credit. Note that numbers above are in units of kilocalories, not kilojoules. R = 1.98 x 10-3 kcal K-1 mol-1

1 Answer

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  • 4 weeks ago

    Why is your prof still using kcal instead of kJ??????

    (Sorry...a small pet peeve of mine.)

    ∆G = ∆Go + RT ln [F-6-P]/[G-6-P] 

    ∆G = 0.4 kcal/mol + (1.98X10^-3)(298K) ln (5X10^-6 / 20X10^-6) = -0.4 kcal/mol

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