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Thermodynamics

Question
CBSEENPH11020503

Two moles of an ideal monoatomic gas occupies a volume V at 27°C. The gas expands adiabatically to a volume 2 V. Calculate (a) the final temperature of the gas and (b) change in its internal energy.

  • (a) 195 K (b) 2.7 kJ

  • (a) 189 K (b) 2.7 kJ

  • (a) 195 K (b) –2.7 kJ

  • (a) 189 K (b) – 2.7 kJ

Solution

D.

(a) 189 K (b) – 2.7 kJ

In an adiabatic Process

TVγ-1 = ConstantOrT1V1γ-1 = T2V2γ-1 For monoatomic gasγ = 53(300)V2/3 = T2(2V)2/3 T2 = 300(2)2/3T2 = 189 K(final temperature)Change in internal energy,U = nf2RT= 232253(-111) = -2.7 kJ