Physical Chemistry: Estimating ΔG of an Ideal Gas

In summary, the problem involves calculating ΔG for a process where one mol of ideal gas is subjected to an increase in pressure from 1.00 atm to 11.0 atm at 25.0°C. The equation ΔG=ΔH-TΔS can be used, and although the heat capacity of the gas is not given, the equation ΔH=C(p,m)(Tf-Ti) can still be used. Additionally, the equation ΔG = nRTln(Pf/Pi) can also be applied for an isothermal process on an ideal gas.
  • #1
Nick_273
9
0

Homework Statement


Estimate ΔG for the process where one mol of ideal gas is subjected to an increase in
pressure from 1.00 atm to 11.0 atm at 25.0°C.


Homework Equations


ΔG=ΔH-TΔS
ΔH=C(p,m)(Tf-Ti


The Attempt at a Solution


Seems straight forward, but it seems i am not given enough information to complete the problem. I need C(p,m)? It does say estimate. Does that mean that i only need to imply that the Gibbs free energy will be possitive, negative, or 0?

If you can help me clarify the problem that would be greatly appreciated!

Thanks.
 
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  • #2
Does the problem say whether the ideal gas is monatomic or diatomic?
 
  • #3
No, it does not. Does this equation apply?

ΔG = nRTln(Pf/Pi)

I found it in my notes but can't find it anywhere in the text.
 
  • #4
Oh, for this case, you can actually still calculate ΔH even though you do not know the heat capacity of the gas.
 
  • #5
Hi Nick_273! :smile:

Nick_273 said:
No, it does not. Does this equation apply?

ΔG = nRTln(Pf/Pi)

I found it in my notes but can't find it anywhere in the text.

Yep, it applies (for an isothermal process on an ideal gas).
 

Related to Physical Chemistry: Estimating ΔG of an Ideal Gas

1. What is the ideal gas law and how is it related to physical chemistry?

The ideal gas law is a fundamental equation in physical chemistry that describes the behavior of an ideal gas. It relates the pressure, volume, temperature, and number of moles of an ideal gas through the equation PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. This equation is used to estimate the thermodynamic properties of gases, such as the ΔG of an ideal gas.

2. How is the ΔG of an ideal gas calculated?

The ΔG of an ideal gas is calculated using the equation ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. This equation takes into account the energy changes associated with the gas's temperature and pressure, as well as the randomness of the gas molecules.

3. What is the significance of estimating ΔG for an ideal gas?

Estimating ΔG for an ideal gas is important in physical chemistry because it allows us to determine the spontaneity of a chemical reaction involving gases. A negative ΔG indicates that the reaction is spontaneous and will proceed without the need for external energy input.

4. How does the ideal gas law account for non-ideal behavior of real gases?

The ideal gas law assumes that gases behave ideally, meaning that they have no volume and there are no intermolecular forces between the gas molecules. However, in reality, gases do have a small volume and there are attractive and repulsive forces between molecules. To account for this, the ideal gas law can be modified with correction factors, such as the compressibility factor, to better estimate the properties of real gases.

5. How does temperature affect the ΔG of an ideal gas?

The temperature has a significant effect on the ΔG of an ideal gas. As the temperature increases, so does the entropy of the gas, which leads to a larger negative value for ΔG. This means that at higher temperatures, the reaction is more likely to be spontaneous. However, if the temperature is too high, the gas may no longer behave ideally and the ideal gas law may not accurately estimate the ΔG.

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