Question

Estimate the average S-F bond energy in `SF_(6)`.The standard heat of formation values of `SF_(6)(g)`, S(g) andF(g) are `: - 1100,275` and`80 Kj mol^(-1)` respectively.

Answer 1

Aim `: (1)/(6) [SF_(6)(g) rarrS(g) +6F(g)],DeltaH=?`
For the reaction , `SF_(6)(g) rarrS(g) + 6F(g)`
`Delta_(f)H = Delta_(f)h^(@) [S(g)+ 6[Delta_(f)H^(@) F (g)]-[Delta_(f)H^(@) SF_(6)(g)=275 + 6(80)-( -1100) kJ mol^(-1) = 1855kJ mol^(-1)`
`:. ` AverageS-F bond energy `= ( 1855)?( 6) =309.16 kJ mol^(-1)`