During isothermal expansion of an ideal gas, its:

Options

A. internal energy increases
B. enthalpy decreases
C. enthalpy remains unaffected
D. enthalpy reduces to zero

Answer

C

Explanation

We know that,
`H=E+W`
Enthalpy =internal energy + pressure `xx` volume
`H=E+pV`
`DeltaH=DeltaE+Delta(pV)`
`DeltaH=DeltaE+Delta(n_(g)RT) " "(because pV=nRT)`
For isothermal expansion of ideal gas , `DeltaT=0`
`therefore DeltaH=DeltaE`