What reactions follow the Law of Conservation of Mass?

Question

Many thanks for answering.

Answer 1

First of all, the system needs to be closed. No mass should leave, and none should enter.

Actually, most chemical reactions do not follow the law of conservation of mass, because the chemical potential energy actually increases the mass of the chemicals. Putting energy into something chemically (for example, hydrolysis on water) increases the mass. However, the change is incredibly miniscule. It is so tiny that it is practically impossible to detect without some very sensitive scale or other setup.

In physics, masses can even change with an increase in speed. No matter how hard you accelerate, you can't get to the speed of light, but the energy you put into acceleration has to go somewhere. It ends up increasing your mass, from the perspective of someone in an outside frame of reference.

Anyway, in general, nuclear reactions are the only ones with changes in mass that most people would care about (of those that care about these reactions in the first place). Small-scale physical reactions and chemical reactions tend to be close enough to conserved-mass reactions that we don't care.

In other words, in a basic sense, only nuclear reactions. The sun, a good example, loses 1.8 million tons or so of its mass every second. Some of that, I think, is solar wind, but a lot of that is from the energy output the sun sustains.

In an advanced view, nothing follows that rule anymore. But the total energy, whether it be potential, kinetic, chemical, electrical, electromagnetic, nuclear, heat, or mass energy, stays the same in a closed system.

Answer 2

this happens because mass cannot be created or destroyed .it is converted from one form to other. lets do it with an example.if you put 29$ in a box which is containing 5$ ,the total money would be29$+5$=34$ and not 35 or 33. the total input you give is the total output you get

Answer 3

All of them. Actually, it is now understood as conservation of mass-energy, since mass and energy are equivalent as shown by the equation E=mc^2.