3 ms·
>Any system that loses energy (e.g. releases an energetic photon - no matter if it's because of a nuclear or chemical reaction) also loses mass Lol sorry my fr
by graerg 5y ago
>Any system that loses energy (e.g. releases an energetic photon - no matter if it's because of a nuclear or chemical reaction) also loses mass
Lol sorry my friend but this is just plain false. Photons can carry away energy in the form of momentum but they're massless. Remember, it's E^2 = (pc)^2 + (mc^2)^2. Nuclear reactions can involve the conversion of mass into energy because they involve the strong force, but that's not how chemical reactions work.
Think about it like this: you have two H atoms bump each other perfectly and come to rest, and in the process an electron gets excited to a higher energy state. Eventually it spontaneously pops back down, emitting a photon that escapes. The mass of the two H atoms is unchanged, but a photon took energy away. It carried away momentum, not mass.
- PeterisP 5y ago"The mass of the two H atoms is unchanged" -> No, if an electron on an H atom is excited to a higher energy state, the mass of the atom increases (although with the relatively low energies involved, that mass increase is extremely tiny). The mass of nucleus isn't equal to the mass of neutrons and protons, the binding energy matters, and the mass of an atom isn't equal to the mass of the nucleus plus the mass of the electrons, the energy states matter. Not an authoritative reference, but perhaps a sufficient explanation is here - https://physics.stackexchange.com/questions/149744/does-the-mass-of-an-electron-change-with-its-energy-state https://physics.stackexchange.com/questions/149744/does-the-...
- graerg 5y agoYou ignored the part where the electron decays back to the lower energy state. The ending states are the exact same as the initial states, since the electron decays back to the lower (initial) state by emitting a photon. The photon carries away momentum, but the mass of the two particles is unchanged.