Is Argus lab accurate?
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was trying to calculate the resonance energy of benzene by using Argus Lab. These values are weird and very different from the experimental data. I have two questions regarding them.
What is the difference between Final SCF Energy and heat of formation?
When I tried to calculate the energy, It gave me two kinds of energy - Final SCF Energy and Heat of Formation. I know the definition of heat of formation. But what I found weird is that Heat of Formation of H2HX2 molecule was −13.3564 kcal/mol−13.3564 kcal/mol. It should be zero instead.
Is there any mistake in following procedure:
a. I calculated the energy of cyclohexane(xx), cyclohexene(yy), and benzene (zz).
b. Energy change while converting cyclohexane to cyclohexene (aa) =y−x=y−x
c. Expected energy for benzene (bb) =x+3a=x+3a
d. Resonance energy of benzene = z−bz−b
(Answer should be negative, implying that resonance energy is stabilizing in nature)
By using the SCF Energy data, I got resonance energy 415 Kcal/mol415 Kcal/mol and while using the heat of formation data I got −41.8 Kcal/mol−41.8 Kcal/mol.
Here is the data (in Kcal/molKcal/mol) -:
Energy typeSCF Energy using PM3Heat Of Formationx−21556.7995−37.43y−20680.6471−3.0101z−18512.618923.96
What is the difference between Final SCF Energy and heat of formation?
When I tried to calculate the energy, It gave me two kinds of energy - Final SCF Energy and Heat of Formation. I know the definition of heat of formation. But what I found weird is that Heat of Formation of H2HX2 molecule was −13.3564 kcal/mol−13.3564 kcal/mol. It should be zero instead.
Is there any mistake in following procedure:
a. I calculated the energy of cyclohexane(xx), cyclohexene(yy), and benzene (zz).
b. Energy change while converting cyclohexane to cyclohexene (aa) =y−x=y−x
c. Expected energy for benzene (bb) =x+3a=x+3a
d. Resonance energy of benzene = z−bz−b
(Answer should be negative, implying that resonance energy is stabilizing in nature)
By using the SCF Energy data, I got resonance energy 415 Kcal/mol415 Kcal/mol and while using the heat of formation data I got −41.8 Kcal/mol−41.8 Kcal/mol.
Here is the data (in Kcal/molKcal/mol) -:
Energy typeSCF Energy using PM3Heat Of Formationx−21556.7995−37.43y−20680.6471−3.0101z−18512.618923.96
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