# mass defect

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#### spacehugo

##### Guest
when i search for "mass defect", all i find is about some complicated nucleus which when join other nucleus loose some mass....... but I belive that i read something about that which goes like this (in short). if you heat up an objekt/mass(in a sealed environment to prevent any kind of leak), it will when cold again, weight less than before it was heated.(and if they put the environment on a scale to see if it gain weight, it did not). have i been dreaming ?

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#### MeteorWayne

##### Guest
Sorry, but I doubt any of us have any idea of what you are talking about. Can you put together a coherent sentence or two to explain?

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#### spacehugo

##### Guest
ok. first of all, i presume you know about mass defect and we spend no more time on that. but my question is as follows:
first you need a container, sealed and insulated.the weight of this container when empty is noticed.inside this container you put 1,00000 gram of iron and what you need to heat up this 1,00000 gram of iron, to f.ex 1200 degrees celsius 10 times.this container you put in a new container, just big enough for the first container, now you have two containers, one inside the other, this steps are repeated, lets say ten times, so you end up with 10 containers each and one inside a bigger one. then you check weight when empty. next you start up the heater and glow the iron f.ex. 2 minutes, turn of heater and let cool down, repeat this step f.ex. 10 times. then you check weight of total, and then you disassemble the containers and check weight of them and the iron. the iron weight less after the heating then before and the containers have not put on the extra weight.
I am not educated so my english must be kept on a low level.

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#### nimbus

##### Guest
Experimentally, it sounds like a bad band-aid fix to use so many boxes instead of a single good insulator. Next, a perfect (perfect enough) insulator would mean that all matter inside is shut in. And 1,200 C heating of pure iron would be just below melting point.. You wouldn't have anything special going on other than that. Which means there would be no conversion of matter to energy. Which (I'm heavily hungover from party, but I'm fairly sure I'm not missing anything) is the only way you would have reduction in mass.

There's many different ways to get to the end state you're curious about, but the one I reckon is most likely is the initial iron lump being impure, and those impurities either leaking out during oven cycles or not being tracked experimentally. E.G. impurities escape iron lump, remain gaseous, then escaping the containers during disassembly because experimenters didn't count on those gas by-products.

So the only other big thing to understand is what you mean when you say mass defect. Impurities?

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#### kelvinzero

##### Guest
Well I found this:

http://en.wikipedia.org/wiki/Binding_energy#Mass_defect

This sounds very similar but not exactly the same as what you are describing. Without a reference, my guess is that this is in fact it, and there is just some confusion in the way you describe it.

There are a number of situations where just counting the protons and neutrons will not give you the exact mass. Total mass will be related to total energy by the good ol' e=mc^2.

Hot iron would weigh very slightly more than cold iron. Even if the process of heating and cooling the iron changed its structure in any way to be lower energy, the mass would be very very sightly less.

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