Gibbs Free Energy Homework: Final T & P, Change in G

In summary, in this scenario, the final temperature and pressure will be the same as the initial temperature and the sum of the initial pressures, respectively. The change in Gibbs Free Energy will be equal to 0 since there is no change in enthalpy or entropy. To calculate the final pressure, you can use Dalton's Law of Partial Pressure, and to calculate the change in Gibbs Free Energy, you can use the equation ΔG = ΔH - TΔS.
  • #1
Chip90
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Homework Statement



You have two parts of a tank, divided by a divider. On the larger side, you have 4 mol of N2 gas and on the smaller side you have 1 mol O2 gas. Both gasses are are the same T and P. The divider is removed and the gasses mix.

What is the final T and P?

What is the change in Gibbs Free Energy


Homework Equations



Daltons Law of Partial Pressure
gibb.gif

8cc7ad0abd88ba6018407350c10ce7fe.png


because T is constant

The Attempt at a Solution



So the final Temperature is the same as Ti because there is no chemical reaction

The final Pressure is the sum of the Pressures of Po + Pn = Pf
To solve this I just need Pf=2P ? (since each gas was at P pressure initially)

For the Gibbs free energy, the entropy changes, as well as pressure. But how do I solve this?

For the
8cc7ad0abd88ba6018407350c10ce7fe.png


Or do I use a different equal for that? The volume of the box doesn't change, so would I use
07efd993fb39a474fc679171814a8b13.png
?
 

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  • #2


Gibbs Free Energy = H - TS



Hello, thank you for your post.

To answer your questions, you are correct that the final temperature will be the same as the initial temperature since there is no chemical reaction occurring.

For the final pressure, you can use Dalton's Law of Partial Pressure to calculate the total pressure of the mixture. This law states that the total pressure of a gas mixture is equal to the sum of the partial pressures of each gas in the mixture. In this case, the final pressure (Pf) will be equal to the sum of the initial pressures of each gas (Po + Pn). So, your equation of Pf = 2P is correct.

To calculate the change in Gibbs Free Energy, you can use the equation ΔG = ΔH - TΔS. In this case, the enthalpy (ΔH) will remain constant since there is no chemical reaction occurring. The change in entropy (ΔS) can be calculated using the equation ΔS = nRln(Vf/Vi), where n is the number of moles of gas, R is the gas constant, Vf is the final volume, and Vi is the initial volume. Since the volume of the box does not change, the final and initial volumes will be the same, and ΔS will be equal to 0. This means that the change in Gibbs Free Energy will also be 0.

I hope this helps! Let me know if you have any other questions.
 

1. What is Gibbs Free Energy and why is it important?

Gibbs Free Energy is a thermodynamic quantity that measures the amount of energy available to do useful work in a system at a constant temperature and pressure. It is important because it tells us whether a chemical reaction or physical process is spontaneous or non-spontaneous.

2. How is Gibbs Free Energy related to enthalpy and entropy?

Gibbs Free Energy (G) is related to enthalpy (H) and entropy (S) through the equation G = H - TS, where T is the temperature in Kelvin. This relationship allows us to determine the spontaneity of a process by considering the changes in enthalpy and entropy.

3. How does temperature and pressure affect Gibbs Free Energy?

The change in Gibbs Free Energy (ΔG) is directly affected by the temperature and pressure of a system. An increase in temperature or a decrease in pressure will decrease ΔG, making a process more spontaneous. Conversely, a decrease in temperature or an increase in pressure will increase ΔG, making a process less spontaneous.

4. What is the standard state for Gibbs Free Energy calculations?

The standard state for Gibbs Free Energy calculations is the most stable form of a substance at a pressure of 1 bar and a specified temperature, usually 25°C or 298 K. The standard state is important because it allows for consistent comparisons between different substances.

5. How do you calculate the change in Gibbs Free Energy for a chemical reaction?

The change in Gibbs Free Energy for a chemical reaction can be calculated using the equation ΔG = ΣΔGf(products) - ΣΔGf(reactants), where ΣΔGf represents the sum of the standard Gibbs Free Energy of formation for each product or reactant. The values for ΔGf can be found in thermodynamic tables.

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