A gas is allowed to expand in a well insulated container against a constant external pressure of `2.5 atm` from an initial volume of `2.50 L` to a final volume of `4.50 L`. The change in internal energy `Delta U` of the gas in joules will be:

Options

A. 1136.23 J
B. `-500 J`
C. `-505 J`
D. `+505 J`

Answer

C

Explanation

`DeltaU=q+w`
For adiabatic process , q=0
`:. DeltaU=w `
`= -P*DeltaV`
`=-2.5 "atm" xx (4.5-2.5)L`
`=2.5 xx 2 L-"atm"`
`=-5xx101.3 J`
`=-506.5 J`
`~~-505 J`