Question

For the reaction,` 2Co +O_(2)rarr 2CO_(2), DeltaH = - 560 kJ `. Two moles of CO and one mole of`O_(2)` are taken in a container of volume 1 L. They completely reacts to form two moles of `CO_(2)`. The gases deviate appreciably from ideal behaviour. Ifthe pressure in the vessel changesfrom 70 to 40 atm,find the magnitude ( absolute value) of `DeltaU` at 500 K `( 1 L atm = 0.1 kJ )`.

Answer 1

`H =U +PV`
`DeltaH+ DeltaU + Delta(PV) ` or ` DeltaH = DeltaU + VDeltaP`
or `DeltaU = DeltaH -VDeltaP = - 560kJ - 1L ( 40 atm -70 atm)`
`=- 560 kJ + 30 Latm = - 560 kJ + 3-0 xx 0.1kJ = - 557 kJ `
Absolute value `=557 kJ . `