Show that for an isothermal expansion of an ideal gas(i)`DeltaU = 0` and(ii) `DeltaH = 0`.

Explanation

(i)For one mole of an ideal gas,`C_(v) = ((DeltaU)/(DeltaT))_(v)`
or `DeltaU = C_(v)DeltaT`
For an isothermal process, T is constant so that
`DeltaT = 0`
`therefore DeltaU = 0`
(ii)`DeltaH = DeltaU + Delta(PV)`
For an ideal gas , PV = RT
`therefore DeltaH = DeltaU + Delta(RT)`
or ` = DeltaU = R DeltaT`
Since T is constant
`DeltaT = 0`
`therefore DeltaH = 0`