Topscore exam 2 # 50 (natural sciences)

[topdent1]

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This question asks to find the standard heat of combustion for a reaction. I always thought the formula for calculating this was heat of products formed subtracted by the heat of reactants. However, in the answer choices, all of them are reactants - products. Am i missing something here?

 

[TheGreenWave]

This question asks to find the standard heat of combustion for a reaction. I always thought the formula for calculating this was heat of products formed subtracted by the heat of reactants. However, in the answer choices, all of them are reactants - products. Am i missing something here?

Ya I was a bit confused too. When you are given the table with bond energies just remember to do bonds BROKEN - bonds FORMED. then you should be straight 👍

 

[Florida premed]

but why is it that bonds broken-bonds formed is divided by two???