could someone show how to get these answers? 1st question answer is Aluminum for
ID: 857089 • Letter: C
Question
could someone show how to get these answers?
1st question answer is
Aluminum forms a layer of aluminum oxide when exposed to air which protects the bulk metal from further corrosion. 4Al(s) + 3O2(g) . 2Al2O3(s) Calculate G degree for this reaction, given that G degree of aluminum oxide is -1576.4 kJ/mol, Calculate G degree for the reaction 3NO2(g) + H2O(l) 2HNO3(l) + NO(g). G degree (kJ/mol) H2O(l) -237.2 HNO3(l) -79.9 NO(g) 86.7 NO2(g) 51.8 Ozone (O3) in the atmosphere can reaction with nitric oxide (NO): O3(g) + NO(g) . NO2(g) + O2(g). Calculate the G degree for this reaction at 25 degree C. Q H degree = -199 kJ/mol, 5 degree = -4.1 JIK-mol) Sodium carbonate can be made by heating sodium bicarbonate: 2NaHCO3(s) Na2CO3(s) + CO2(g) + H2O(g) Given that H degree = 128.9 kJ/mol and O G degree = 33.1 kJ/mol at 25 degree C, above what minimum temperature will the reaction become spontaneous under standard state conditions?Explanation / Answer
Q#1
4Al + 3O2 ===>2Al2O3
DelHfo (Al2O3)=-1576.4kJ/mole
for pure substances like O2 and Al
DelHfo (O2)=0 kJ/mole
DelHfo (Al)=0 kJ/mole
DelHfo(rxn)=Sum[DelHfo(pro)]-Sum[DelHfo(rect)]
DelHfo(rxn)=2DelHfo (Al2O3)-Sum[DelHfo(rect)]=2*(-1576.4kJ/mole)-0 =-3152.8kJ/mole
Q#2
DelHfo(rxn)=Sum[DelHfo(pro)]-Sum[DelHfo(rect)]
DelHfo(rxn)=2DelHfo(HNO3) + DelHfo(NO)-3DelHfo(NO2) + DelHfo(H2O)
DelHfo(rxn)=2(-79.9)+86.7 -3(51.8)+237.2=8.7kJ
Q#3
T=25oC=298.15K
DelGo=DelHo-TDelSo=-199kJ/mole-298.15K(-0.0041kJ/K-mole)=-197.8kJ
Q#4
DelGo=DelHo-TDelSo
T=(DelHo-DelGo)/DelSo=(128.9kJ/mole-33.1kJ/mole)/DelSo=95.8/DelSo
for reaction to be spontaneous DelSo<0
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