Exothermic/endothermic vs. exergonic/endergonic and ATP

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I am confused about the following:

So breaking ATP --> ADPi +Pi is exergonic (spontaneous so -dG)
forming ATP is endergonic

While if you look at exothermic/endothermic, forming bonds is exothermic and breaking bonds is endothermic.

So then does that mean breaking ATP is endothermic and exergonic??? because you are breaking a bond and it's spontaneous.. I am confused..is that possible?

Basically if something is exergonic, it doesn't mean that it is EXOTHERMIC as well, right? You have to look at dH before deciding?

Hey

Endothermic means you have to put more energy in to break it than it gives off

Exothermic menas you have to in less energy to make it than it gives off.

looks at graphs it may help. im not sure what you are trying to ask.

Originally Posted by theleatherwalle

Hey

Endothermic means you have to put more energy in to break it than it gives off

Exothermic menas you have to in less energy to make it than it gives off.

looks at graphs it may help. im not sure what you are trying to ask.

When you break ATP into ADPi and Pi...it's considered an exergonic reaction..but since we are breaking bonds does that mean that it's and endothermic reaction? this is what i was trying to ask

so you are basically saying that i would need exact values to be able to determine whether it's exothermic or endothermic?

This is my understanding off it. I havn't done this in quite awhile.

So you obviously have to put in energy to break apart ATP, but ADP and P+ give off more energy than you put in.

Also remember endergonic and endothermic don't mean the same thing.

Does that answer your question. I would suggest talking to a gen chem buff, i am not that person.

Originally Posted by diene

I am confused about the following:

So breaking ATP --> ADPi +Pi is exergonic (spontaneous so -dG)
forming ATP is endergonic

While if you look at exothermic/endothermic, forming bonds is exothermic and breaking bonds is endothermic.

So then does that mean breaking ATP is endothermic and exergonic??? because you are breaking a bond and it's spontaneous.. I am confused..is that possible?

Basically if something is exergonic, it doesn't mean that it is EXOTHERMIC as well, right? You have to look at dH before deciding?

exergonic means the system releases energy during reaction
exothermic means the system releases heat during reaction

exergonic does not necessary mean that it is exothermic or vice versa
since free energy=enthalpy-(temperature)(entropy)
you can still get -G and be +enthalpy(endotherminc) if you have a positive entropy at high temperature

for ATP->ADP+Pi it is for sure exergonic since ATP is high potential energy molecule and breaking the bonds of ATP is much less than the energy that is released, but you can't tell whether exotherminc/endothermic from that (since -G and +S, you can either have -H or +H)

in order to determine the enthalpy of breaking the bond you need numerical numbers or at least +/- of free energy and +/- of entropy

just remember dG=dH+TdS
and -dG is spontaneous and +dG is nonspontaneous

Great explanation ^^ thanks.