Question about Gibb's Free Energy and Equilibrium

In summary, the conversation discusses the reaction ATP + H2O -> ADP + H2PO4- and its equilibrium conditions, with a focus on the direction of the reaction and the maximum work that can be done under standard state conditions. The calculated value for Delta(G) at 23C and various concentrations suggests that the reaction shifts to the right. However, the question of maximum work becomes irrelevant at such high concentrations, as activities would need to be used instead of concentrations. The practical relevance of this question is also questioned.
  • #1
reyrey389
24
0
for the reaction ATP + H2O -> ADP + H2PO4- Delta(G^0)= -30.5 kj/mol

A)if 0.5 mol of ATP, 1 mol of H2O, 1.5 mol of ADP, and 0.2 mol of H2PO4- are mixed in a 2.2L container at 23C, which direction would the reaction shift to reach equilibrium? I used Delta(G) = Delta(G^0) + RT*ln(Q) I used 0.273 for Q and got Delta(G) to be -33.69 kJ/mol and that the reaction shifts to the right.
Can someone check this?

B) "what is the maximum work that can be done by this reaction under standard state conditions?"
i know i use Delta(G) = W_max, but would I need to change all concentrations to 1 Molar first since it asks for standard states?
 
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  • #2
reyrey389 said:
for the reaction ATP + H2O -> ADP + H2PO4- Delta(G^0)= -30.5 kj/mol

A)if 0.5 mol of ATP, 1 mol of H2O, 1.5 mol of ADP, and 0.2 mol of H2PO4- are mixed in a 2.2L container at 23C, which direction would the reaction shift to reach equilibrium? I used Delta(G) = Delta(G^0) + RT*ln(Q) I used 0.273 for Q and got Delta(G) to be -33.69 kJ/mol and that the reaction shifts to the right.
Can someone check this?

B) "what is the maximum work that can be done by this reaction under standard state conditions?"
i know i use Delta(G) = W_max, but would I need to change all concentrations to 1 Molar first since it asks for standard states?
In principle yes but
at these high concentrations it makes no sense to use concentrations. You would have to use activities.
The question is completely void of any practical relevance if not chemical impossible. Where is it from?
 

1. What is Gibb's Free Energy and how is it related to equilibrium?

Gibb's Free Energy is a thermodynamic quantity that measures the maximum amount of energy that can be extracted from a system to do useful work at a constant temperature and pressure. It is related to equilibrium because at equilibrium, the Gibb's Free Energy is at its minimum value, indicating that the system is stable and no spontaneous changes will occur.

2. How is Gibb's Free Energy calculated?

Gibb's Free Energy (G) is calculated using the equation G = H - TS, where H is the enthalpy (total energy) of the system, T is the absolute temperature, and S is the entropy (degree of disorder) of the system. This equation takes into account both the energy available in the system and the amount of disorder, giving a more accurate measure of a system's stability.

3. Can Gibb's Free Energy be negative?

Yes, Gibb's Free Energy can be negative. A negative value for G indicates that the system is spontaneous and will proceed towards equilibrium. This means that at a given temperature and pressure, the reactants will spontaneously form the products, releasing energy in the process.

4. How does temperature affect Gibb's Free Energy and equilibrium?

Temperature affects both Gibb's Free Energy and equilibrium. As temperature increases, the entropy of a system also increases, causing the Gibb's Free Energy to decrease. In turn, this can shift the equilibrium towards the products in an exothermic reaction, where the products have a lower Gibb's Free Energy. In an endothermic reaction, an increase in temperature can shift the equilibrium towards the reactants, as they have a lower Gibb's Free Energy at higher temperatures.

5. Can Gibb's Free Energy be used to predict the spontaneity of a reaction?

Yes, Gibb's Free Energy can be used to predict the spontaneity of a reaction. If the calculated value for G is negative, the reaction is spontaneous and will proceed towards equilibrium. If the value is positive, the reaction is non-spontaneous and will not occur without an external energy source. If the value is zero, the system is at equilibrium.

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