Question

A container is filled with 20 moles of an ideal
diatomic gas at absolute temperature T. When
heat is supplied to gas temperature remains
constant but 8 moles dissociate into atoms. Heat
energy given to gas is
(1) 4RT
(2) 6RT
(3) 3RT
(4) 5RT​

Answer 1

HELLO....

A container filled with n1 = 20 moles of ideal diatomic gas at absolute temperature T. when heat is supplied to gas temperature remains constant but n2 = 8 molesdissociated into atoms. Heat energy given to gas is Solution Since the gas is enclosed in a vessel, therefore, during heating process, volume of the gas remains constant. Hence, no work is done by the gas. It means heat supplied to the gas is used to increase its internal energy only. Initial internal energy of the gas is U1 =n1(5/2 RT ). Since n moles get dissociated into atoms, therefore, after heating, vessel contains (n1 − n2) moles of diatomic gas and 2n2 moles of a mono-atomic gas. Hence the internal energy for the gas, after heating, will be equal to U2 =(n1 − n2)5/2RT +2n2*3/2RT = 5/2n1RT + n2RT/2

Hence, the heat supplied is equal to the increase in internal energy

U2-U1 = 4RT.

HENCE OPTION 1. IS THE RIGHT ANSWER....

HOPE IT'S HELPS....

Answer 2

Answer:

Heat  energy given to gas is 4RT .

Explanation:

We know :

Energy of 20 moles of diatomic gas , $E_1=\dfrac{5}{2}nRT = 50RT\ .$

Now , average energy of renaming 12 moles of diatomic gas + average energy of 16 moles of mono atomic gas ( since each mole of diatomic gas gives 2 moles of mono atomic gas ).

Therefore , $E_2=\dfrac{5}{2}\times ( 12RT)+\dfrac{3}{2}\times (16RT)=54RT\ .$

So, heat supply = Final energy - Initial energy

H = 54RT-50RT

H=4RT.

Hence , this is the required solution .