Calculating Molar Gibbs Function

In summary, the molar Gibbs function, G-G0, at 2000K for BSi can be calculated using the equation G-G0 = -kT ln(Z) + nRT, where Z is the partition function. The individual contributions to Z include Z_e, representing the degeneracy of the ground state, Z_v, representing the volume term, Z_r, representing the rotational term, and Z_n, representing the vibrational term. After calculating each of these contributions, they can be plugged into the equation for G-G0 and solved for the final result.
  • #1
LeePhilip01
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Homework Statement


For this question I'm to calculate the molar Gibbs function, G-G0, at 2000K for BSi given that the bond distance is 1.905[itex]A^{\circ}[/itex], [itex]ω^{~}[/itex] = 772cm-1, the ground electronic state has a degeneracy of 4, and the lowest energy excited electronic state, 8000cm-1 above the ground state, also has a degeneracy of 4.


Homework Equations


Gibbs Function G = H-TS ... (1)

where H is enthalpy, T is temperature and S is entropy.


G-G0 = -kT ln(Z) + nRT ... (2)


The Attempt at a Solution


So since it's molar I'm assuming there's going to be a volume term somewhere (in calculating partition function) and V=0.02446m3.

Do I need to work out all the individual contributions to the partition function, Z, then just simply plug them into (2) ?
 
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  • #2
$G-G0 = -kT ln(Z) + nRT$ Where,$Z= Z_eZ_vZ_rZ_n$ $Z_e = 4$ (degeneracy of ground state) $Z_v = \frac{V}{h^3}$ (I think...) $Z_r = \frac{1}{2\pi mkT}$ (?) $Z_n = \frac{1}{2\pi hc}\int_{0}^{\infty}\frac{\omega^2}{e^{\frac{\omega}{kT}}-1}d\omega$ and then plugging into (2) I get $G-G0 = -kT ln\big(\frac{V}{h^3}\frac{1}{2\pi mkT}\frac{1}{2\pi hc}\int_{0}^{\infty}\frac{\omega^2}{e^{\frac{\omega}{kT}}-1}d\omega\big)+ nRT$
 

Related to Calculating Molar Gibbs Function

What is the definition of Molar Gibbs Function?

The Molar Gibbs Function, also known as the Gibbs Free Energy, is a thermodynamic quantity that measures the amount of energy available for a chemical reaction to occur at a constant pressure and temperature. It is denoted by the symbol G and has units of energy per mole.

How is the Molar Gibbs Function calculated?

The Molar Gibbs Function can be calculated using the equation G = H - TS, where H is the enthalpy, T is the temperature in Kelvin, and S is the entropy. This equation is based on the fundamental thermodynamic relationship known as the Gibbs-Helmholtz equation.

What is the significance of the Molar Gibbs Function?

The Molar Gibbs Function is a crucial tool in determining whether a chemical reaction will occur spontaneously. If the value of G is negative, the reaction is thermodynamically favorable and will occur without the need for external energy. If the value of G is positive, the reaction will not occur spontaneously and will require an input of energy.

How does temperature affect the Molar Gibbs Function?

The temperature has a direct effect on the Molar Gibbs Function. As temperature increases, the value of G becomes more negative for exothermic reactions, making them more favorable. However, for endothermic reactions, a higher temperature will make the value of G more positive, making the reaction less favorable.

What are the units of Molar Gibbs Function?

The units of Molar Gibbs Function are energy per mole, typically joules per mole (J/mol) in the SI system. However, it can also be expressed in other units such as calories per mole (cal/mol) or kilojoules per mole (kJ/mol).

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