O chem destroyer Question

[Jonbrout]

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Problem #90. It's simple but maybe i'm remember enthalpy incorrectly.

Br2 --------hv-----> 2 Br radicals.

what would you think is true about delta H?

I was under the impression for this reaction delta H would be negative (exothermic) because with increase in disorder comes increase in movement and thus increase in heat.

The manual says delta H is positive (endothermic). Could you clear this up for me. Thanks for your help.

 

[SavBJJ]

t if i had to venture a guess Id say delta H is endothermic because youre breaking the Br-Br bond which would require an input of energy (hv). Breaking bonds has + delta H and forming bonds has - delta H.

THe question doesnt really seem to require thinking about entropy (delta S), which would increase in the reaction, but idk, hopefully someone can answer your question but it seems pretty straightforward to me.

 

[Jonbrout]

I believe it just confused me since it is only saying we are using hv (so light), and not a head source (delta). I do realize it takes an input of energy to break bonds. Thanks anywho

Edit: the rest of the problem has to do with entropy ( + delta S) from disorder. just fyi. I was just confused with the delta H part though.

 

[SN2ed]

Thread moved. These types of questions belong in the Study Q&A forum.