Case:1 I have one iron spring. I compress it gives potential energy E= ½* K*x2 & bind it by glass wire which is not melted in acid. Now I put this spring in acid & it melted completely, So where the potential energy gone? Case:2 I put one magnet in glass vessel & hold it in vessel by some mechanical means. I put another magnet outside of vessel in such a way that there is a repulsive force between them & so both magnet possesses potential energy w.r.t. each other. Now I pour acid in vessel & magnet inside vessel is melted, So where the potential energy gone? Case:3 I charge capacitor & break it. Both the charged plate taking outside carefully so it not get discharged. Previously the energy which is in the dielectric media, now where is that energy? If I destroy both the plate of capacitor by throwing it into acid OR furnace, How the energy will conserve which I have given to charge the capacitor? Please for giving answer take suitable acid & material. Please give explanation from microscopic point of view also, so I can understand better.