A `3` mole sample of a triatomic ideal gas at `300 K` is allowed to expand under adiabatic reversible condition from `5L` to `40 L`. The value of `DeltaH` is

Options

A. `-12.46` KJ
B. `-14.965` KJ
C. `-24.62` KJ
D. `-10.24` KJ

Answer

B

Explanation

For triatomic gas
`gamma =1.33, C_(p) = 4R`
`T_(2) = T_(1)(V_(1)/V_(2))^(y-1)`
`=300 xx (5/40)^(1.33-1) = 300 xx (1/8)^(1//3) = 300 xx 1//2 = 150`
`DeltaH = nC_(2)(T_(2)-T_(1))= 3 xx 4 xx 8.314 xx (150-300) = -14.965` KJ
Hence, B is the correct answer.