5 moles of Hydrogen initially at S.T.P. are compressed adiabatically so that its temperature becomes
. The increase in the internal energy of the gas in kilo-joules is:
21.55
41.50
65.55
80.55
By convention, the work done on the gas is taken to be negative, i.e. W = −41.5 kJ From
the first law of thermodynamics dQ = dU + dW For an adiabatic process, dQ = 0
Hence dU = −dW = −(−41.5) = 41.5 kJ The positive sign of dU implies that the
internal energy increases