Boltzmann Distribution (Chemistry/ Physics)

AI Thread Summary
The discussion revolves around two questions related to the Boltzmann distribution and thermodynamic parameters. The first question asks how many molecules of the hyperstoichiometric compound Al3O are in the ground state at 300K and 3000K, utilizing the Boltzmann equation for vibrational energy spacing. The second question involves calculating the number of protein molecules unfolded at 300K using calorimetric data, with participants expressing confusion over the appropriate equations and the role of ΔCp. There is a suggestion to explore the relationship between ΔS and ΔCp to better understand the unfolding process. Overall, the thread highlights the complexities of applying the Boltzmann distribution and thermodynamic principles in these scenarios.
Klestine
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Homework Statement


Okay i want to ask 2 questions.
Question 1
Hyperstoichiometric compound Al3O has a vibrational energy spacing of 3.08x 10^-21J
how many molecules are present in the ground state at 300k and 3000K

Question 2
Calirimetric data for protein unfolding yielded following thermodynamic parameters
Parameter
ΔH (Tr) 220kJ/mol
ΔS (Tr) 0.68 kJ/mol/K
ΔCp 2.5 kJ/mol/K
how many protein molecules unfolded at 300K

Homework Equations


For question 1
Shown below is the Boltzmann equation
nj/ni = e-(Ej-Ei)/KT

Grond state equation is
nj/n0 = e-(Ej)/KT (this I found in a textbook)

For question 2

ΔG=ΔH-TΔS

The Attempt at a Solution



Okay for question the equation given in lecture notes is different to the equation i found in textbooks and the internet and it is

n0 = n(1-e-(ΔE)/KT

Two equations are confusing me, the this is if i use the equation given under relevant equations I get a weird answer,obviously wrong. Using the equation given in lecture notes it is easy and straight forward, but i doubt if it correct!

and for question 2 i have no clue what so ever to be honest. I do not know how i can use ΔCp

Thank you very much in advance for your help

Homework Statement


Homework Equations


The Attempt at a Solution


Homework Statement


Homework Equations


The Attempt at a Solution

 
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With the Boltzmann equation, you would have to consider all states (and add their relative probabilities), as this just gives a relative probability. Your equation at (3.) did take this into account, you can use it.

Question 2: No idea.
 
Klestine said:

Homework Statement


Okay i want to ask 2 questions.
Question 1
Hyperstoichiometric compound Al3O has a vibrational energy spacing of 3.08x 10^-21J
how many molecules are present in the ground state at 300k and 3000K

Question 2
Calorimetric data for protein unfolding yielded following thermodynamic parameters
Parameter
ΔH (Tr) 220kJ/mol
ΔS (Tr) 0.68 kJ/mol/K
ΔCp 2.5 kJ/mol/K
how many protein molecules unfolded at 300K

Homework Equations


For question 1
Shown below is the Boltzmann equation
nj/ni = e-(Ej-Ei)/KT

Grond state equation is
nj/n0 = e-(Ej)/KT (this I found in a textbook)

For question 2

ΔG=ΔH-TΔS


The Attempt at a Solution



Okay for question the equation given in lecture notes is different to the equation i found in textbooks and the internet and it is

n0 = n(1-e-(ΔE)/KT

Two equations are confusing me, the this is if i use the equation given under relevant equations I get a weird answer,obviously wrong. Using the equation given in lecture notes it is easy and straight forward, but i doubt if it correct!

and for question 2 i have no clue what so ever to be honest. I do not know how i can use ΔCp

Thank you very much in advance for your help
Question 2 looks like fun! :biggrin:

Think about what the link between ΔS and CP (\Delta S = nC_p ln\frac{T}{T_0}) means for the system.
 
thanx guys, question 2 is fun and an absolute killer
 
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