One mole of an ideal monatomic gas undergoes an adiabatic expansion in which its volume becomes eight times…

One mole of an ideal monatomic gas undergoes an adiabatic expansion in which its volume becomes eight times its initial value. If the initial temperature of the gas is 100K and the universal gas constant R=8.0 J mol-1 K-1, then how much is the decrease in its internal energy (in J) ?

Solution

Vi=V
Vf=8V
For adiabatic process {γ=5/3 for monoatomic gas}
T 1 V 1 γ1 = T 2 V 2 γ1
100V23=T28V23
T2=25 K
Loss in internal energy U=nCvT=1fR2100-25=12×75=900 J ^

Asked in: JEE Advanced 2018 (Paper 2)

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