(a) What happens to the enthalpy during this reaction? Explain.

(b) What happens to the entropy during this reaction? Explain.

all help is appreciated, thank you!
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answers:
Dr W say: dHrxn = dHf(products) - dHf(reactants)
dSrxn = dSf(products) - dSf(reactants)

from these tables
https://en.wikipedia.org/wiki/Standard_e...
http://www.mrbigler.com/misc/energy-of-f...
https://www.chemeo.com/cid/45-400-7/Octa...

species.. .. . ..dHf (kJ/mol).. .. .. .. .. .dSf (J/molK)
C8H18(l).. .. .. .. -208.4.. ... .. .. ... .. .+359.8
O2(g).. ... ... ... .. .. .0.. ... ... ... .. ... . .+205.0
CO2(g).. .. ... .. .. -393.5.. ... ... ... .. . +213.6
H2O(g).. ... ... ... .-241.8.. .. ... .. ... .. +188.7

so.. for the reaction
.. 2 C8H18 + 25 O2 ---> 16 CO2 + 18 H2O

dHrxn = (16*(-393.5) + 18*(-241.8)) - (2*(-208.4) - 25*(0)) = -10200 kJ

dSrxn = (16*(214) + 18*(189)) - (2*(360) - 25*(205)) = +621 J/molK
'
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the - value for dHrxn means energy is given off by the reaction. We all know that right? we burn gasoline and heat is given off

why do you suppose dS is + ???
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wfect say: ospegrks
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wfipo say: rovtrkgz
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