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Author Topic: Does an endothermic reaction gain mass?  (Read 6054 times)

Patrick Poisson

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Does an endothermic reaction gain mass?
« on: 29/01/2009 21:30:05 »
Patrick Poisson  asked the Naked Scientists:
   
Does an endothermic reaction produce an end product heavier than its constituent parts prior to the reaction?

i.e. was some amount of matter created from energy drawn from the surrounding system and conversely does an exothermic reaction convert a miniscule amount of matter into energy?  

If the endothermic reaction end-product is heavier, then what is the additional mass comprised/made of?

What do you think?


 

Offline Chemistry4me

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Does an endothermic reaction gain mass?
« Reply #1 on: 29/01/2009 23:22:04 »
Why does everyone want to know about stuff gaining matter? You think it's fun do you?
« Last Edit: 30/01/2009 00:06:06 by Chemistry4me »
 

Offline Make it Lady

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Does an endothermic reaction gain mass?
« Reply #2 on: 29/01/2009 23:24:03 »
Yes! the reaction is an implosion of space into outer shells of the reactant atoms.

(Ithink someone has gained weight resently!)
 

Offline Chemistry4me

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Does an endothermic reaction gain mass?
« Reply #3 on: 29/01/2009 23:42:55 »
(Ithink someone has gained weight resently!)
???
 

Offline Chemistry4me

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Does an endothermic reaction gain mass?
« Reply #4 on: 30/01/2009 00:16:52 »
If the endothermic reaction end-product is heavier, then what is the additional mass comprised/made of?
Matter is a static (un-moving), usually fairly concentrated state of energy, and energy itself has mass at all times, no matter what form it is in. Exothermic and endothermic chemical reactions are just the result of the difference in the bond energies of bonds broken and bonds formed, not mass conversion.
« Last Edit: 30/01/2009 00:18:35 by Chemistry4me »
 

Offline lightarrow

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Does an endothermic reaction gain mass?
« Reply #5 on: 30/01/2009 12:03:23 »
Patrick Poisson  asked the Naked Scientists:
   
Does an endothermic reaction produce an end product heavier than its constituent parts prior to the reaction?
Yes, but please, be careful: the mere fact it's *endothermic* doesn't mean anything; what counts is the fact that the reaction system *absorbs* or not heat from the surrounding. If you have an endothermic reaction in a thermally isolated container, then the system cannot assume energy from the surrounding and so it cannot increase its mass. In this case the system just decreases its temperature and its mass remain the same.

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i.e. was some amount of matter created from energy drawn from the surrounding system and conversely does an exothermic reaction convert a miniscule amount of matter into energy?
It depends on which form has the energy; if a hotter surrounding heats up your system through conduction or convection, then there is no energy conversion at all: simply the surrounding has transferred mass to your system; if instead the surrounding heats your system through electromagnetic radiation, then there is mass/energy conversion: the surrounding loses mass emitting energy in the form of EM radiation, then your system acquires mass absorbing that energy.

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If the endothermic reaction end-product is heavier, then what is the additional mass comprised/made of?
Is made of the increased energy it has. You shouldn't think of energy→matter conversion as something that necessary generates new particles. Mass is nothing else than energy in a fixed region of space. Light has no mass when it's "free" because there isn't a fixed region of space which has that energy (you can't find a frame of reference stationary with respect to light).
But if you inject a light beam inside a box which has reflecting internal walls, then the box *does* acquire mass, because now you have confined the light in a fixed region of space.
I now that this is difficult to understand, because we were indoctrinated to think about mass as something completely different from energy. It was a genius as Einstein who understood it's not so.
« Last Edit: 30/01/2009 12:08:48 by lightarrow »
 

Offline lightarrow

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Does an endothermic reaction gain mass?
« Reply #6 on: 30/01/2009 12:10:30 »
energy itself has mass at all times, no matter what form it is in.
This is not correct, a beam of light has no mass.
 

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Does an endothermic reaction gain mass?
« Reply #6 on: 30/01/2009 12:10:30 »

 

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