Achiever: G chem 2 # 70

[TheWiredNerv]

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They ask you to figure out the average bond energy of N-F in NF3. I know how to do these problems fairly well but I got it wrong. However, in the solution they did dH = Reactants - Products instead of Products - Reactants. Is this just an error on DAT Achiever's part?

 

[fancymylotus]

They ask you to figure out the average bond energy of N-F in NF3. I know how to do these problems fairly well but I got it wrong. However, in the solution they did dH = Reactants - Products instead of Products - Reactants. Is this just an error on DAT Achiever's part?

Nope. Delta H= Bonds broken-Bonds formed.

 

[TheWiredNerv]

I see the error in my ways!
Then when do you use Products - Reactants?

 

[fancymylotus]

I see the error in my ways!
Then when do you use Products - Reactants?

This is totally unscientific and all, but it helped me to memorize it or whatever. For EVERYTHING else(entropy,heat of formation,hess,etc) it goes products-reactants. Bond energies are the only ones that are reactants-products.

 

[TheWiredNerv]

that works perfectly fine 😀