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)))^(gamma - 1)`
`= 300 ((5)/(40))^((1)/(3))`
`= 300 ((1)/(8))^((1)/(3)) = 300 xx (1)/(2) = 150`
`DeltaH = n xx C_(P) (T_(2) - T_(1))`
`= 3 xx 4 xx 8.314 (150 - 300)`
`= - 14.965 kJ`