# Section E Flashcards Preview

## CH3717 Statistical Mechanics > Section E > Flashcards

Flashcards in Section E Deck (10)
1
Q

Equpartition

A

relates temperature of a system to its average energies

2
Q

Vibrational internal energy

A

at high tem

3
Q

Diatomic linear molecule

A

has 2 degrees of freedom

4
Q

a non-linear molecule

A

3 derees of freedom

5
Q

Vibrational modes

A

contributes two increments of 1/2 kT to the internal energy, U.

• 1/2 from Kinetic and 1/2 from Potential
• = 1 = U= kT per vibrational mode
• U = RT per mole per molecule
6
Q

slide 5 (vibrational mode) only happens at what?

A

HIGH TEMPERATURE

- most vibrational modes of most moleucles at room temp, even the first excited state almost has no occupancy

7
Q

AT high temp

A

T is substantially big compared to theta vib

8
Q

at low temp

A

the exponential term gets very big (almost all the population is in the ground state)

9
Q

Electronic internal energy

A
• usually the lowest lying electronic states have a relative energy greater thena kT
• but if there are unusually low lying states with energy similar to kT, then they will be thermally populated
• we would have to calculate the populations and internal energy explicitly from the measured energies of the state. (generally not a simple formula for this)
10
Q

translational entropy

A
• for non-linear molecules, 1, 2 or 3 rotational degrees of freedom
• linear molecules have 2 rotational degrees of freedom