Question

A monatomic gas (ideal) is supplied 80 joule heat at constant pressure. the internal energy of gas, increases by

Answer 1

Given heat supplied Q=80 J

As mentioned in question the process undergoes constant pressure process (Isobaric process)

We know heat supplied is given as

Q =nCΔT -----(A) also

work done W=nRΔT-----(B)

Now relating equation A and B we get,

 {Q/CpΔT} = {W/RΔT}

{QR/Cp}=W-----(1)

Again we know,

{R/Cp} = {γ-1/γ}-----(C)

and the value of γ for mono atomic gas=5/3-----(E)

Now reducing the value of C and D in 1 we get

80×{(5/3)-1}{5/3}=W

W= - 64 J ( negative sign indicates work done is by the system)

Now from thermodynamic law we get

Q = ΔE+W

ΔE=Q-W=80-(-64)

ΔE=144 J