Substance or chemical reaction, that is highest rate in changing mass

[roineust]

Hello!

What would be the substance, chemical reaction and technique, to have the highest rate of immediate mass change, back and forth, from low to high and back to low again, as many times as needed - using only homemade DIY, non dangerous materials and equipment?

My intentions are to deal in the range of 1-250 grams.

What would be the change under these DIY home limitations?

Would it be a change of between, say, 10 grams and 10.2 grams or is there some marvelous material mass transforming 'magic', that can make 10 grams become 100 grams, almost instantly and then again, almost instantly or when needed, back to 10 grams?

I understand that this questions might uncover some basic misunderstanding of some elementary modern physics principles (i hope not of classical physics as well...), but that's the situation here and we shall appreciate a detailed, as well as simple answer as possible!

Thanks!

 

[mfb]

Chemical reactions never change the masses*. In some reactions, you can create gases that escape, or use parts of the atmosphere (like oxygen) to bind it to your other materials, but the total mass of the products is always the same as the total mass of the chemicals used for the reaction.
This is purely classical physics - after the reaction you have the same atoms as before, just in a different arrangement.

*apart from extremely tiny relativistic effects way too small to be relevant

 

[roineust]

Thanks,
But is there any technique, to bind oxygen from the air, to a certain substance, up to a needed level and then to release the same amount or oxygen or other non harmful gas and have these changes very fast and at such a mass change level, that can be felt at a tactile level? say, at least a difference of +- 5 grams? or am i still misunderstanding some basic physical/chemical principle?

 

[mfb]

I doubt that. Most reactions with oxygen (or nitrogen) release so much heat that they are hard to reverse - even if you are lucky and don't produce escaping water vapor or CO2 in the reaction. And even if you find such a reaction, you would have to heat the material in such a way that it does not react with oxygen again afterwards.

A 1-way reaction is easier. Just burn wood ;).

Fuel cells can reach +- 5 grams if you can store ~5 liters of hydrogen, but that is a very slow process and you need significant electric energy to reverse the reaction - and the setup will have a significant weight so you don't note a difference of 5 grams without a scale.

 

[roineust]

Gotcha!
Thanks!