IIT JEE past question Thermodynamics 4

At 27 degree C two moles of an ideal monoatomic gas occupy a volume V. The gas expands adiabatically to volume 2V
calculate the final temp, change in internal energy and work done.

10 Answers

21
tapanmast Vora ·

Adiabatic = Reversible OR Irreversible ??

62
Lokesh Verma ·

is that needed?

3
iitimcomin ·

TV5/3-1 = T2 ((2)V)5/3-1

T = T2(22/3)

300/(22/3) = T2

2R/(2/3) (T2-T)

3
iitimcomin ·

W= -dU ........

21
tapanmast Vora ·

Point!

its not given that Constant Ext. Pressure or nethin lyk dat,

Then v can take REVERSIBLE, jus lyk IITIM... took

1
skygirl ·

hmm.......

T1=300K. V1=V. V2=2V. T2=?

mnoatomic => Cv=3/2, Cp=5/2 , γ=5/3

TVγ-1 = constant.

300.V2/3 = T2. (2V)2/3

=> [300/T2] = 34

=> T2 = 300/ 34 K.

1
skygirl ·

oops posted already ! din c sorry........

1
skygirl ·

ΔU= nCvΔT. = 2X3/2X (300 - 300/34)

= 3.(300 - 300/34)

work done = nR(T1-T2)/(γ-1) all the terms we know already.

11
Mani Pal Singh ·

FOR TEMPERATURE USE
T1VIγ-1=T2V2γ-1

WE GET P1=23/5P2
AND 22/5T1=T2

T1=300K

SO

300 X 22/5=T2

ΔE =nCvdt

=3/2 x 2 x R x (300 X 22/5-300)

as it is adiabatic so ΔQ=0

by applying ΔE=ΔQ-ΔW

we can find the work done

11
Mani Pal Singh ·

iska answer aise nahin karna kya ????

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