Answer to Question #85145 in Molecular Physics | Thermodynamics for Abhishek Dogra

Question

A vessel contains a non-linear triatomic gas. If 50% of gas dissociate into individual atom, then find new value of degree of freedom by ignoring the vibrational mode and any further dissociation.
(1) 2.15
(2) 3.75
(3) 4
(4) 1.09

Answer 1

Let's assume that we have 1 mole of triatomic gas.

Therefore 3NA (Avogardo's Number) is present initially.

So, 0.5 moles has 1.5NA atoms.

Now, 1 part of 0.5 moles remains undissociated.

So. degree of dissociation = 0.5 x 6 = 3

The other 0.5 moles has 1.5NA which breaks into 3 atoms.

So, total number of atoms = 0.5NA

Now, degree of freedom for monoatomic gas = 3

So, degree of freedom for 0.5NA monoatomic particles = 1.5 x 0.5 = 0.75

Hence, total will be 3 + 0.75 = 3.75

which is the required answer.

(2) 3.75