Question

A gas is allowed to expand at constant temperature from a volume of `1.0 L` to `10.0 L` against an external pressure of `0.50` atm. If the gas absorbs `250 J` of heat from the surroundings, what are the values of `q` and `DeltaE` ? (Given `1 L "atm" =101 J`)
A. `{:(q,w,DeltaE),(250J,-455J,-205J):}`
B. `{:(q,w,DeltaE),(-250J,-455J,-710J):}`
C. `{:(q,w,DeltaE),(250J,455J,710J):}`
D. `{:(q,w,DeltaE),(250J,455J,205J):}`

Answer 1

Correct Answer - A
`q="heat absorbed"=+250 J`
`W=-PDeltaV=-0.5"atm"xx(10-1)`
`=-4.5 L-"atm"`
`=-4.5xx101J=-454.5 J`
Now `q=DeltaE-W`
`DeltaE=q+W=250-454.5`
`=-204.5 J`