Question

When a system of acetone undergoes a phase change from liquid to vapor, the entropy change (ΔS) for the system is 95 J/K and it requires 31.3 kJ of energy to be transferred into the system from the surroundings.

(CH3)2CO (l) → (CH3)2CO (g) ΔH = 31.3kJ

a. Calculate the overall entropy change (ΔSuniverse) for this process at 65.0°C.

b. Briefly discuss whether or not this process would be spontaneous or nonspontaneous at this temperature.

Answer 1

We know that 1 Stotal = D Spysen + DS surrounding ] A Stotal is the entropy change of Gniverse only for is a reaction et constant last by surrounding and Temp. and gained by pressure system, of heat then IDS surrounding = - q - indicates heat loss, We know pressure at constant 190=Dn Thus, substituting this value, we get.. As wrounding - - An Thus DS total - DS system - An the desired for mula used to solve the This is question.

(W Given. Srystin = 95J/k = 95 X103 kJ/K. Dh= 31.3 kJ T= 65°C = 65+ 273.15 = 338.15 K. Sunivers = DSpor = DS nystem - AH hers tal т . = 95X103 - 313 338.15 Taking L.COM As universe. = (0.0958 338.15) - 31.3 338.15 AS univers = 2.424 X10 J Asuniverse = 242 4 J/k.)

We derived A total = D D > TDS total = TDS-DH Systen we know DG DH-TDS Thus, ITDS totul = - ] uince DG is positive as we have will be negative calculated in and hence are the a thus, process will oh be spontaneous.
i have also derived the desired formula used .

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