Question

Cells use the hydrolysis of adenosine triphosphate, abbreviated as ATP, as a source of energy. Symbolically, this reaction can be written as

ATP (aq) + H₂O(l) → ADP(aq) + H₂PO₄(aq)
where ADP represents adenosine diphosphate. For this reaction, AG-30.5 kJ/mol
Calculate K at 25°C.
(Enter your answer to two significant figures.)
K = ____

Answer 1

The equilibrium constant (K) for the hydrolysis of ATP to ADP and Pi at 25°C is approximately 2.3 x 10⁵, calculated using the Gibbs free energy change and the universal gas constant.

Step-by-step explanation:

Cells use the hydrolysis of adenosine triphosphate (ATP) as a source of energy. During hydrolysis, ATP is converted into adenosine diphosphate (ADP) and inorganic phosphate (Pi), with the release of energy. The reaction can be represented as ATP + H₂O → ADP + Pi.

This process is exergonic, meaning it releases free energy, which is captured and used for various cellular processes through energy coupling.

The Gibbs free energy change (ΔG) for this reaction under standard conditions is -30.5 kJ/mol, which can be used to calculate the equilibrium constant (K) at a given temperature using the relationship ΔG = -RTlnK, where R is the universal gas constant and T is the temperature in Kelvin.

To calculate K at 25°C (298K):

K = exp(-ΔG/(RT))

K = exp(30500 J/mol / (8.314 J/(mol·K) · 298 K))

K = exp(30500 / 2475.252)

K ≈ exp(12.33)

K ≈ 226000

Therefore, the equilibrium constant (K) for the hydrolysis of ATP to ADP and Pi at 25°C is approximately 226000, or 2.3 x 10⁵ to two significant figures.