Piston cylinder device initially contains `0.5m^(3)` of nitrogen gas at `400 kPa` and `27^(@)C`. An electric heater within the device is turned on and is allowed to apss a current of `2 A` for `5 mi n` from a `120 V` source. Nitrogen expands at constant pressure and a heat loss of `2800 J` occurs during the process.
`R=25//3 kJ //k mol - K`
Electric work done on the nitrogen gas is

Options

A. `72 kJ`
B. `36 kJ`
C. `118 kJ`
D. `9kJ`

Answer

A

Explanation

Electric work done on the nitrogen
`W_(e)=-Delta VIDeltaT`
`=-120 xx 2 xx 5 xx 60=72 xx 10^(3)J`
`=-72 kJ`
`(` Negative sign is added because the work is done on the system `)`.