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Topic: endo/exothermic bond formation  (Read 14289 times)

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Offline benzenejamie

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endo/exothermic bond formation
« on: December 25, 2008, 07:13:03 AM »
when new bonds are formed is more energy absorbed or released if the new bond is STRONGER than the previous one?

Offline macman104

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Re: endo/exothermic bond formation
« Reply #1 on: December 25, 2008, 11:31:19 AM »
when new bonds are formed is more energy absorbed or released if the new bond is STRONGER than the previous one?
What do you think?  Is energy released or put into a system if you want to break a bond?  Is energy released or put into a system when you form a bond?

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #2 on: December 26, 2008, 02:20:35 PM »
i think more energy is released if the new bond is stronger but wasnt sure if there were exceptions

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #3 on: December 26, 2008, 03:29:50 PM »
are you going to tell me if i am right or not?
do you even know yourself or do you just like to throw people's question back at them?
do you think i would have posted if i didnt have any doubts or even gave it a little bit of consideration?
 

Offline macman104

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Re: endo/exothermic bond formation
« Reply #4 on: December 26, 2008, 03:37:04 PM »
are you going to tell me if i am right or not?
do you even know yourself or do you just like to throw people's question back at them?
do you think i would have posted if i didnt have any doubts or even gave it a little bit of consideration?
Um...wow?  Sorry, I didn't respond within your beloved time-frame of an hour after you posted your highness  ::).

First off: I posted my questions because on this forum, we don't just give out answers.  We ask you questions to try and get you to arrive at the answer yourself.  This way, if another question similar comes around, you have already reasoned one similar to it, and the chances of successfully answering another like it increases.

Secondly:  See, you answered the question without me giving you the solution and you answered correctly!  So maybe, your second post should have been your question instead of your first post:

"I believe that more energy is released if you break a bond and form a new stronger bond, but I wasn't sure if there were exceptions".  That would have been more informative, since you knew the first part, no?

So no, as far as I am aware, there are no exceptions to this rule.  Energy is required to break a bond, and energy is released when you form a bond, and off the top of my head, I cannot think of any exceptions to your question.

Politeness goes a long way around here my friend.

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #5 on: December 26, 2008, 05:34:03 PM »
first off mr mac my second post was not a question. it was simply my own unsubstantiated guess.
and secondly...i am not in a rush for your reply. Many people come on here and throw comments around and never follow them up.
I found it extremely foolish of you to post a comment to a simple question asking me to think about it. Maybe there are people who post things without giving ANY consideration to the answer. But I believe that MOST humans posting here have at least thought about the answer to their question at least ONCE.
It may have been more polite of you to provide an example if you wanted to teach me or lead me in the right direction. You havent even done that in your final answer. You have simply offered me your understanding which for the most part am not sure if it is even correct.

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #6 on: December 26, 2008, 05:55:16 PM »
when new bonds are formed is more energy absorbed or released if the new bond is STRONGER than the previous one?
What do you think?  Is energy released or put into a system if you want to break a bond?  Is energy released or put into a system when you form a bond?

Just wanted to comment on this. You ask "is energy released or put into a system when you form a bond?"
The fact of the matter is that some new bonds formed release energy and some absorb energy. Some reactions are exothermic and other endo. The question I was posing from the start was...if the new bond is STRONGER than the original, does that mean it was necessarily an exothermic reaction...or can an endothermic reaction actually prove a stronger bond in some cases.
We both seem to believe it is only with exo.

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #7 on: December 26, 2008, 06:01:39 PM »
So no, as far as I am aware, there are no exceptions to this rule.  Energy is required to break a bond, and energy is released when you form a bond, and off the top of my head, I cannot think of any exceptions to your question.
I also want to correct you on this statement. Yes energy is required to break a bond. However if the reaction is endothermic the new bonds are absorbing energy. Im just assuming that this bond is WEAKER.

Offline macman104

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Re: endo/exothermic bond formation
« Reply #8 on: December 27, 2008, 01:59:27 AM »
and secondly...i am not in a rush for your reply. Many people come on here and throw comments around and never follow them up.
I don't observe that much, it may be true, not sure.  Usually if someone is left hanging, they'll post and say "please help me", or something like that.
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I found it extremely foolish of you to post a comment to a simple question asking me to think about it.
That is how this forum works.  If you post a quesiton, but you don't show any attempt to answer or reason out the question yourself, then it is assumed you may not know.  So then, the next step is to help point you in the right direction and lead you to the answer, which is what I tried to do.
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Maybe there are people who post things without giving ANY consideration to the answer. But I believe that MOST humans posting here have at least thought about the answer to their question at least ONCE.
Oh, how completely wrong you are.  I wish it were true, but it just isn't.
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It may have been more polite of you to provide an example if you wanted to teach me or lead me in the right direction. You havent even done that in your final answer. You have simply offered me your understanding which for the most part am not sure if it is even correct.
I said I agreed with your answer, however, looking back, I think there may have been a miscommunication.

Here was the distinction. 

In all cases, and as far as my chemical understanding is, when a bond is formed, energy is released, period.  However, we are considering this in a vacuum, of what happens when a bond is formed.  However, this is not considering a system where we have reactants and products.

When we have reactants and products:

If the products bonds have a higher potential energy (endothermic), they will be less stable, and will require energy input, thus an OVERALL energy input.  However!  That does not mean that when the physical bond is formed, energy is not released.

If the products bonds have a lower potential energy (exothermic), then they will be more stable, and will require energy input, thsu an overall energy OUTPUT.

I hope that is clear, and sufficiently answers your question.  Let me know what is left that is not clear.

Offline macman104

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Re: endo/exothermic bond formation
« Reply #9 on: December 27, 2008, 04:14:55 PM »
In all cases, and as far as my chemical understanding is, when a bond is formed, energy is released, period.  However, we are considering this in a vacuum, of what happens when a bond is formed.  However, this is not considering a system where we have reactants and products.

When we have reactants and products:

If the products bonds have a higher potential energy (endothermic), they will be less stable, and will require energy input, thus an OVERALL energy input.  However!  That does not mean that when the physical bond is formed, energy is not released.

If the products bonds have a lower potential energy (exothermic), then they will be more stable, and will require energy input, thsu an overall energy OUTPUT.
I'm rewording this because I was not completely in my right mind last night, and there are some cut/paste issues:

In all cases, and as far as my chemical understanding is, when a bond is formed, energy is released, period.  However, we are considering this only for what happens when a bond is formed.  This is not considering a system where we have reactants and products.

When we have reactants and products:

If the products bonds have a higher potential energy (endothermic), they will be less stable, and will require energy to be put into the system, for an OVERALL input of energy.  However!  Just because the overall reaction is endothermic, the bond forming process is still one that releases energy, just not as much as what was put into the system.

If the products bonds have a lower potential energy (exothermic), then they will be more stable, and will not require any extra energy input.  Energy is put in to break the bonds of the reactants (or they may break apart themselves).  When the products formed, energy will be released when the bonds form, however, these products have a lower potential energy, and the energy released is going to be greater than whatever was put into the system, for an overall OUTPUT.

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #10 on: December 28, 2008, 05:10:45 AM »
here is my original question:
when new bonds are formed is more energy absorbed or released if the new bond is STRONGER than the previous one?
You explain that every new bond being formed requires energy (endo) and releases energy (exo) upon being formed.

In your explanation you use the word stable. I used the word stronger. In my mind I am visuallizing a system in eq such as
I2(g)+H2(g)<-->2HIg
both reactions are taking place simultaneous
the system is stable

Im going to quote you:
 "we are considering this in a vacuum, of what happens when a bond is formed.  However, this is not considering a system where we have reactants and products."
and then you reword yourself:
"In all cases, and as far as my chemical understanding is, when a bond is formed, energy is released, period.  However, we are considering this only for what happens when a bond is formed.  This is not considering a system where we have reactants and products."

I have 2 questions for you:
1) I have no idea what you mean by vacuum. Can you explain this please
2) how can you form a bond "without a reactant"?



Offline macman104

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Re: endo/exothermic bond formation
« Reply #11 on: December 28, 2008, 10:53:45 AM »
Quote
I have 2 questions for you:
1) I have no idea what you mean by vacuum. Can you explain this please
2) how can you form a bond "without a reactant"
Sorry, I mean, vacuum, in the sense that we aren't considering anything else, just the bond forming process.  So we would look at the bond forming process regardless of what the actual reaction is.  When we do this, I'm saying that as far as I know, it is always an energy releasing action (when the physical chemical bonds form, there is a release of energy).  I'm not forming a bond "without a reactant" exactly, I'm just not considering the whole system when I'm looking at the bond forming process.

However, the key aspect is that during a reaction, there may or may not be an energy input required in order for the actual reaction to proceed.  When we look at a reaction, we can classify exo and endo by the location of the reactants and products on a potential energy diagram.  If the reactants are at a higher potential energy (weaker, less stable, etc) than the products, then there will be a net energy release (exo).  If the reactants are at a lower potential energy (stronger, more stable, etc) than the products, then there will be a net energy input (endo).

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #12 on: December 29, 2008, 03:12:02 AM »
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However, the key aspect is that during a reaction, there may or may not be an energy input required in order for the actual reaction to proceed. 

can you provide an example

Offline macman104

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Re: endo/exothermic bond formation
« Reply #13 on: December 29, 2008, 03:22:28 AM »
No energy input required:  Mixing concentrated acid with water, highly exothermic!
Energy input required:  Ammonium Nitrate and Water (a cold pack), very endothermic, absorbs energy from surroundings

Is that what you meant by example?

Offline benzenejamie

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Re: endo/exothermic bond formation
« Reply #14 on: January 04, 2009, 06:29:47 AM »
so you are saying an acid water reaction like this:
H2SO4 + H2O → H3O+ + HSO4−
is a TOTALLY exothermic reaction
THAT NO ENERGY IS REQUIRED FOR THIS REACTION TO OCCUR
is that correct?

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