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2 votes
0 answers
90 views

Why does $\rm{H_2 O}$ have 12 degrees of freedom?

I know there will be 3 translational D.O.F. and 3 rotational D.O.F., and it can have 4 vibrational D.O.F. (one potential and one kinetic) for each O-H Bond. But from where does 2 more D.O.F. come from?...
Ujjwal's user avatar
  • 41
0 votes
1 answer
86 views

Difference between Kopp-Neumann and Dulong-Petit law?

So this is basically a follow-up to this question: How many degrees of freedom does the water molecule have? I've done some further research and found that the main difference between Dulong-Petit and ...
Zedssad's user avatar
  • 85
1 vote
1 answer
428 views

Why is the heat capacity of water $9R$ and not $6R$?

From the equipartition theorem, the relationship between energy and temperature in a substance is $U=\frac{NRT}{2}$ for $N$ quadratic degrees of freedom associated with a particle of that substance. ...
cbushofsky's user avatar
0 votes
1 answer
1k views

Is there a way to calculate the number of degrees of freedom of water?

Say we have liquid water. We are given specific heat of water $C=4.2kJ(kg*K)$, a number of molecules in a mol $N_A=6*10^{23}$. The atomic weight of water is $18g/mol$, and the Boltzmann's constant is $...
Jerry Holmes's user avatar
2 votes
1 answer
1k views

How many degrees of freedom would water have at $\rm 500K$?

At this temperature, and lower, the rotational degrees of freedom would already be in action, then at this higher temperature id think vibration degrees of freedom are no longer frozen out. So this ...
David's user avatar
  • 433
0 votes
0 answers
331 views

What is the internal energy of water vapor? OR How many degrees of freedom does $\rm H_2O$ have?

Here are the "knowns" that I'm working with. Internal Energy for a monatomic gas is $$U = (3/2)nRT$$ For a diatomic gas its $$U = (5/2)nRT$$ All of my textbooks and online sources indicate ...
Physicator's user avatar
7 votes
1 answer
259 views

Specific heat capacity vs KE gain of particles

To increase the temperature of 1kg of water by 1C you need 4200J of energy. However, the KE gain is only $\frac{3}{2} k_B \Delta T \cdot 6.02\cdot 10^{23} \cdot \frac{1000}{18} = 692.3$J. Where does ...
Edward Garemo's user avatar
1 vote
1 answer
16k views

Why does water have 9 degrees of freedom and that too all vibrational?

How does water has 9 degrees of freedom? If it can vibrate about all three atoms then why can't a diatomic molecule also have 2 instead of 1 possible vibrations? I haven't studied quantum mechanics ...
Matt's user avatar
  • 644
4 votes
0 answers
103 views

What is the deepest cause of the such high specific heat capacity of water?

Yes, I know about the hydrogen bridges. But I think, it isn't the deepest cause. Anyway, they are only second-order bindings, although quite strong. I think, somehow should have the water a ...
peterh's user avatar
  • 8,338