How Does Temperature Affect Vibrational State Populations in Molecules?

In summary, the task is to use the Boltzmann expression to find the vibrational state populations for D2, F2, and I2 molecules at 389 K and 1899 K. The vibrational quantum numbers for each molecule are given, along with the assumption that gv = go = 1. After applying the equation Nv/No=(gv/go)* e^(– (Ev –Eo) /kT), the values for Nv/No are found to be 0.0059 and 0.0001 for D2 at 389 K and 1899 K, respectively; 0.0178 and
  • #1
SilentBob1988
1
0

Homework Statement



Use the Boltzmann expression where v is the vibrational quantum number to complete the following table.

Vibrational State Populations

Molecule

D2 (v=3115)
F2 (v=917)
I2 (v=214.5)

Find Nv/No for 389 K and 1899 K

Assume gv = go = 1

Homework Equations



Nv/No=(gv/go)* e^(– (Ev –Eo) /kT)

The Attempt at a Solution



I have no idea how to even start. :(

I'm not sure how to do it but the Ev-Eo term aren't Es, they are Epsilon symbols.
 
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  • #2
So it's the energy difference between vibrational states. And the kT term is referred to as the Boltzmann factor. For D2:Nv/No (389 K) = (1/1)* e^(– (3115 - 0) / (1.38x 10^-23 x 389)) = 0.0059Nv/No (1899 K) = (1/1)* e^(– (3115 - 0) / (1.38x 10^-23 x 1899)) = 0.0001For F2:Nv/No (389 K) = (1/1)* e^(– (917 - 0) / (1.38x 10^-23 x 389)) = 0.0178Nv/No (1899 K) = (1/1)* e^(– (917 - 0) / (1.38x 10^-23 x 1899)) = 0.0004For I2:Nv/No (389 K) = (1/1)* e^(– (214.5 - 0) / (1.38x 10^-23 x 389)) = 0.0762Nv/No (1899 K) = (1/1)* e^(– (214.5 - 0) / (1.38
 

Related to How Does Temperature Affect Vibrational State Populations in Molecules?

What is the Boltzmann expression?

The Boltzmann expression is a mathematical formula that relates the probability of a particle being in a specific energy state to the temperature and energy levels of a system. It was developed by Austrian physicist Ludwig Boltzmann in the late 19th century and is an important concept in statistical mechanics.

What does the Boltzmann expression tell us?

The Boltzmann expression tells us about the distribution of particles among energy states in a system at a given temperature. It helps us understand the behavior of gases and other systems at the microscopic level, and is used to calculate important thermodynamic properties such as entropy and free energy.

What is the significance of the Boltzmann constant in the expression?

The Boltzmann constant, denoted by k, is a fundamental constant of nature that relates energy to temperature. It appears in the Boltzmann expression as a proportionality constant and helps us convert between energy and temperature units. Its value is approximately 1.38 x 10^-23 joules per kelvin.

What are some real-world applications of the Boltzmann expression?

The Boltzmann expression is used in a wide range of fields, including physics, chemistry, engineering, and materials science. It is used to study gas behavior, chemical reactions, and the properties of materials at different temperatures. It is also essential in understanding and predicting the behavior of complex systems such as biological molecules and atmospheric gases.

How does the Boltzmann expression relate to the second law of thermodynamics?

The Boltzmann expression is closely related to the second law of thermodynamics, which states that the total entropy of a closed system tends to increase over time. The expression helps us understand how the distribution of particles among energy states affects the entropy of a system, and how this relates to the overall behavior of the system over time.

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