Question

The free energy obtained from the oxidation (reaction with oxygen) of glucose (C6H12O6) to form carbon dioxide and water can be used to re-form ATP by driving the above reaction in reverse. Calculate the standard free energy change for the oxidation of glucose.

Answer 1

The oxidation of one mole of glucose with a standard free energy change of -687Kcal/mole can produce approximately 94 moles of ATP, considering it takes about 7.3 Kcal to synthesize one mole of ATP.

Step-by-step explanation:

The student has asked about the calculation of standard free energy change for the oxidation of glucose and how many moles of ATP are produced by burning a mole of glucose. The standard free energy change (DGo) for the oxidation of glucose (C6H12O6) to form carbon dioxide (CO2) and water (H2O) is approximately -687Kcal/mole. Given that it takes about 7.3 Kcal to synthesize one mole of ATP, the number of moles of ATP produced can be calculated by dividing the total amount of energy released by the energy cost to make one mole of ATP.

Using the equation:
687 Kcal/mole ÷ 7.3 Kcal/mole of ATP = number of moles of ATP

We can calculate that approximately 94 moles of ATP may be produced from the complete oxidation of one mole of glucose.

Answer 2

The correct answer is -2878 kJ/mol.

Step-by-step explanation:

The reaction that takes place at the time of the oxidation of glucose is,

C₆H₁₂O₆ (s) + 6O₂ (g) ⇒ 6CO₂ (g) + 6H₂O (l)

The standard free energy change for the oxidation of glucose can be determined by using the formula,

ΔG°rxn = ∑nΔG°f (products) - ∑nΔG°f (reactants)

The ΔG°f for glucose is -910.56 kJ/mol, for oxygen is 0 kJ/mol, for H2O -237.14 kJ/mol and for CO2 is -394.39 kJ/mol.

Therefore, ΔG°rxn = 6 (-237.14) + 6 (-394.39) - (-910.56)

ΔG°rxn = -2878 kJ/mol