Thermodynamics and Thermochemistry 2 Question 17

17. Estimate the average SF bond energy in $\mathrm{SF}{6}.Thevaluesofstandardenthalpyofformationof\mathrm{SF}{6}(g), \mathrm{S}(g)and\mathrm{F}(g)are:-1100,275and80 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. (1999, 3M)

Show Answer

Solution:

  1. SF6(g)S(g)+6 F(g)

ΔH=ΣΔHf (products) ΣΔHf (reactants)

=275+6×80+1100=1855 kJ

Average SF bond energy =18556=309.16 kJ/mol