An ideal gas undergoes isothermal expansion at constant pressure. During the process:

Question

An ideal gas undergoes isothermal expansion at constant pressure. During the process: (A) Enthalpy remains constant but entropy increases (B) Enthalpy decreases but entropy increases (C) Enthalpy increases but entropy decreases (D) Both enthalpy and entropy remain constant

Tardigrade Admin · Accepted Answer

textΔH text= textnC textp textΔT text= text0, ∴ textΔT text= text0 ∴ Pext = defined so process is irreversible. textΔS text= textnRln (( textV) textf ( text/V) texti) ≥ text0

Q. An ideal gas undergoes isothermal expansion at constant pressure. During the process:

Enthalpy remains constant but entropy increases

Enthalpy decreases but entropy increases

Enthalpy increases but entropy decreases

Both enthalpy and entropy remain constant

$ΔH = nC_{p} ΔT = 0, ∴ ΔT = 0$
$∴$ P_ext = defined
so process is irreversible.
$ΔS = nRln ((V)_{f} (/V)_{i}) \geq 0$

Q. An ideal gas undergoes isothermal expansion at constant pressure. During the process:

Enthalpy remains constant but entropy increases

Enthalpy decreases but entropy increases

Enthalpy increases but entropy decreases

Both enthalpy and entropy remain constant

ΔH=nCp​ΔT=0,∴ΔT=0 ∴ Pext = defined so process is irreversible. ΔS=nRln ((V)f​(/V)i​)≥0

$ΔH = nC_{p} ΔT = 0, ∴ ΔT = 0$
$∴$ P_ext = defined
so process is irreversible.
$ΔS = nRln ((V)_{f} (/V)_{i}) \geq 0$