Question

8. Metals can exist as liquids at hundreds of degrees below their melting point. The normal melting point of gold is 1064°C where AH fus = 12.55 kJ mol-. Deeply supercooled gold has been observed at 834°C. Given that Cp.m(s) = 25.418, and Cpm(l) = 29. 29 J mol-? K-, consider the change in entropy when one mole of supercooled gold at 834°C freezes isothermally. Determine AS for a) the system (the gold) and [-20 < AS <OJ K-] b) the surroundings. c) Is the process spontaneous? Why or why not?

Answer 1

It freuzes at 834°C. this the process]. Now as it freezes it Releaseshiat of Jusion olgusion weenow a mol o fusion - 12.55 KJ .. weenow ds = (do for Gold. us = sa y o fusion since it Garaso IT system Sold = -12.55 X 1000 Je (834+273) A gold = -11.33694 5/K for assurs = Alfusion = 12.58X1000 Tahmosphie (270). I presume (25°c)

m ossur - 45.1433 TL OG = BH - T Osgood ) - 12550 (40.7) (-11.33694) A gold = 0 LG System - 12550 - 2788 45.1433 20 - Stotal = S god to our 33.80636 5/6 Hence Rx his feasible as entopy of universe must alway Increas. ..
See the gold is at 834°C when it is freezed , this freezed at temperature below it's melting point{possible}

Heat is released to freeze the gold , this is the process where we freeze the gold from liquid to solid

Now see a rxn is said spontaneous if ∆S is positive of universe as it will decrease will ∆G below o and this is what we require. For spontaneous process

Now usually surrounding temperature is at 25°C which I have taken the case

A process is possible of ∆S of universe increases

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