PLEASE HELP :) Exothermic and Endothermic Watch

abbiewilko15
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So I am incredibly baffled right now is breaking bonds endothermic or exothermic? And is making bonds exothermic or endothermic?

You would think that breaking a bond would release energy and that is what I have learnt in a level Biology. But in chemistry I was told that breaking a bond uses up energy and is hence endothermic?

Is there special circumstances or a rule eg only true for certain bonds or is one of my teachers just talking nonsene
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ambiplasma
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It'd require work to break a bond so that'd be endothermic I think?
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BobbJo
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You need to put in energy to break a bond. So bond breaking is endothermic. Conversely bond forming is exothermic

Hydrolysis of ATP releases energy because it is an exothermic process. The system changes to a state of lower free energy.
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charco
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(Original post by abbiewilko15)
So I am incredibly baffled right now is breaking bonds endothermic or exothermic? And is making bonds exothermic or endothermic?

You would think that breaking a bond would release energy and that is what I have learnt in a level Biology. But in chemistry I was told that breaking a bond uses up energy and is hence endothermic?

Is there special circumstances or a rule eg only true for certain bonds or is one of my teachers just talking nonsene
Just ask yourself a question.

If you have a glass paperweight in front of you, can you break it without putting in energy?

Well bonds are like the glasss paperweight. If you want to break them you have to apply energy.

Never, but never listen to biologists unless you want advice about the correct pencil to use for colouring leaves ...
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abbiewilko15
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(Original post by BobbJo)
You need to put in energy to break a bond. So bond breaking is endothermic. Conversely bond forming is exothermic

Hydrolysis of ATP releases energy because it is an exothermic process. The system changes to a state of lower free energy.
Ahh thank you so much! I know this is a bit specific but is there any way you could explain how breaking the bond on the extra phosphate on activated nucleotides causes the release of energy to make the phosphate backbone. If you dont actually study biology or have no clue what Im on about dont worry 😂
I havent studied the hyrdolysis of ATP but Im assuming its the same as other hydrolysis reactions such as of maltose into glucoses.
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iLoveRodents
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You need energy to separate two atoms that want to be together.

:hugs:(You'd require energy to push apart these huggers - after all they want to cling together)

However when they join together and make a bond, they release energy - like heat or sparks.

:jumphug:(But when they join together, they'd release noise and kinetic energy.)

Reactions may be endothermic or exothermic overall as the energy required to break the bonds may be smaller or greater than the energy to make new ones.

I don't know the context of your biology, so I can't say why they may have said that.
I know that I am taught ATP -> ADP + Pi + energy. This isn't the entire reaction. It also involves water to make it, and thus bonds are also made, releasing energy.
I hope this helps in someway!
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BobbJo
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(Original post by abbiewilko15)
Ahh thank you so much! I know this is a bit specific but is there any way you could explain how breaking the bond on the extra phosphate on activated nucleotides causes the release of energy to make the phosphate backbone. If you dont actually study biology or have no clue what Im on about dont worry 😂
I havent studied the hyrdolysis of ATP but Im assuming its the same as other hydrolysis reactions such as of maltose into glucoses.
I assume you are talking about DNA replication

It requires energy to phosphorylate the nucleotides. The activated nucleotides release this energy when the phosphoanhydride bond is cleaved. I guess you can think of it as dephosphorylation being the reverse of this process (of activating nucleotides), hence releasing energy.

If the system goes to a state of lower free energy, the process releases energy and is exothermic. All hydrolysis reactions are not necessarily exothermic though. It depends on what you're hydrolysing, e.g halogenoalkane, ester, amide, acid anhydride, disaccharide, ...
It's not really that simple!

The simplest thing you should recall is that bond breaking is endothermic and bond making is exothermic.
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