Question

In a container, two mole of a diatomic ideal gas is allowed to expand against 1 atm pressure and volume change from 2 L to 5 L. Calculate the change in Internal Energy.

Answer 1

Given Data

Pressure = 1 atm

V1 = 2 L

V2 =5 L

Solution:

W = P Δ V = n R Δ T

As,

Δ T = P Δ V / n R

Δ T = 1 ( 5 - 2) / 2 x 0.0821

Δ T = 18.27 K

Δ U = n Cv Δ T

In case of diatomic gas,

Cv = 5/2 R

ΔU= 2 x 5/2 x 8.314 x 18.27

ΔU= 760K

Answer 2

it's volume increases and according to Boyle's law PV=constant. So,as volume increases.....pressure decreases. As PV/T is constant according to combined gas law, temperature remains constant.