Calculating S-F Bond Energy in SF6 using Standard Heat of Formation Values

[harambe]

Homework Statement

Estimate the average S-F bond energy in SF6 The standard heat of formation values of SF6(g) , S(g) and F)(g) are: -1100, 275 and 80 kj / mol respectively.

Homework Equations

∆H=∆Hf (products) -∆Hf(Reactants)

S(g) +6F)(g) ------>SF6(g)

The Attempt at a Solution

I found the ∆H formation of the reaction which I got -1455 kJ/ mol and taking this as my bond energy. But My answer doesn't match so can you tell me what am I doing wrong [/B]

 

[Borek]

I found the ∆H formation of the reaction which I got -1455 kJ/ mol and taking this as my bond energy.

That would be true for a molecule with SF formula.

 

[mjc123]

First, your calculation of ∆H is wrong; you have only taken account of one F. Second, how many S-F bonds are formed in the reaction? How do you work out the average energy per bond? Third, bond energy is the energy released by forming a bond, or the energy consumed by breaking a bond - it is a positive quantity. How is it related to ∆H?

 

[alejandromeira]

First, your calculation of ∆H is wrong;

Yes, -1455kJ/mol is not the right answer.

Harambe, you need to answer questions like: how many bonds thee are in the reagents, how many bonds there are in the products... also the request energy is only for 1 bond.