delta Sf (AL2O3) = 50.92 J/molK
delta Sf (O2) = 205.14 J/molK
delta Sf (Al) = 28.33 J/molK
Reaction taking place is:
4Al +3 O2 --->2Al2O3
a.
delts S sys = delta Sf (products) - delta Sf (reactsnta)
                    Â
= 2*delta Sf (Al2O3) - 4* delta Sf (Al) - 3*delta Sf (O2)
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= 2*(50.92) - 4*(28.33) -3*(205.14)
                     Â
= -626.9 J/molK
b.
q sys= delta H = -3351.4 KJ/mol = -3351400 J/mol
q surr = -qsys = 3351400 J/mol
I am assuming tempearture os 298 K
delta S surrounding = qsurr/T
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=3351400/298
                                          Â
= 11246.3 J/molK
c.
delta S univ = delta S sys +delta S surr
                        Â
= -626.9 +11246.31
                         Â
= 10619.4 J/molK