How does the free energy change of ATP hydrolysis inside a living cell compare with the standard value?

1. The standard calculation assumes pH 7.0, 25 degrees Celsius and 100 kilopascals, which are not the conditions inside a cell. 2. Cellular conditions vary considerably from these standards, so a different value is expected there. 3. The free energy change for hydrolysis of one mole of ATP in a living cell is almost double the value at standard conditions. 4. Doubling makes ATP hydrolysis a stronger energy source in the cell than the textbook standard figure suggests. 5. A value equal to the standard would contradict the point that cellular conditions differ. 6. The reaction still releases energy in the cell, so its sign does not flip to positive. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 6 "Metabolism", section 6.4 ATP: Adenosine Triphosphate_