Pressure of 10 moles of an ideal gas is changed from 2 atm to 1 at against constant external pressure without change in temperature. If surrounding temperature (300K) and pressure (1 atm) always remains constant then calculate total entropy change `(DeltaS_("system")+DeltaS_("surrounding"))` for given process.
[Given : ? n2 = 0.70 and R = 8.0 J/mol/K]

Options

A. `56J//K`
B. `14 J//K`
C. `16 J//K`
D. None of these

Answer

C

Explanation

`DeltaS("System")= nRT In (P_(1))/(P_(2))" "= 10 xx 8 xxIn 2 = 80 xx 0.7 = 56`
`DeltaS _(surr) = - (q_(irr))/(T)=(W_(irr))/(T)`
`= - (P_(ext)((nRT)/(P_(2))-(nRT)/(P_(1))))/(T)`
`=- 10 xx R xx (1)/(2) = - 5R`
` = - 40 J`