Law of Conservation of Mass Reading Comprehension

The scientifically correct term for the discipline of this article is mass, which is non, strictly speaking, the same every bit weight. But, for all practical purposes, the 2 can be considered to be the same. It's just what a scale would tell y'all if you counterbalance something.

The Constabulary of Mass Conservation states that the total mass in an isolated sysstem remains constant, regardless of the processes taking place in that organization.

This is intuitively obvious for unproblematic mechanical actions: If you have a coffee maker apart, the pieces weigh as much as the original java maker. For chemic transformations, this is not so obvious.

This law was a evolution of inquiry in the 18th and 19th centuries, notably Antoine Lavoisier'southward experimental discovery that, when all substances were properly accounted for—specifically gases, during the process of combustion—the total weight of a closed system is not inverse by a chemical reaction. A great deal of careful research went into this law—gases are not like shooting fish in a barrel to weigh. Note that volume is not preserved in chemical reactions (or in taking apart a coffee maker). But mass was found to be preserved.

As an example of this in the field of chemistry, the combination of 22.99 grams of Sodium with 35.45 grams of Chlorine (those quantities are one mole each, or Avogadro'due south number of atoms) yields 58.44 grams of Sodium Chloride.

Radioactivity and Nuclear Physics

Over time, the understanding of this principle has developed. But in the early twentieth century it became clear that radioactivity seemed to violate both the Police force of Mass Conservation and the classic "Constabulary of Conservation of Elements". It was found that small changes in mass occur when elements undergo radioactive disintegration. The consequence was only observed for nuclear transformations. For a while this led to the belief that the law does not apply to nuclear reactions, and holds only for other phenomena. This false notion may still be taught to some elementary-school children.

That notion is non truthful. It would imply that nuclear phenomena involve a different sort of primal physics (laws of motion, etc.) from other phenomena. But that isn't so—the key laws of physics at are the same for all phenomena.

The caption relates to potential energy. Recall that, from the Police force of Free energy Conservation, energy is conserved. Kinetic energy (the energy of motion that you tin "meet" such as a ball falling) may seem to disappear, but information technology is actually only turning into potential energy. That "hidden" potential energy can be turned back into kinetic energy. The sum of potential energy and kinetic energy is constant.

Hither are the of import points:

• Potential energy has mass.

• When potential free energy is converted to kinetic energy, that mass simply disappears. Conversely, when kinetic energy is converted to potential energy, that mass comes into existence. The Law of Mass Conservation does not cover that potential-energy-equivalent mass, though you lot could weigh information technology on a calibration.

• The conversion factor is one.eleventen^-17 kilograms per Joule.

That conversion factor is so tiny that the scientific customs can be forgiven for not noticing the effect for so long. For case, the chemical reaction of Sodium and Chlorine to create Sodium Chloride is exothermic and releases a few hundred one thousand Joules per mole. (The exact amount depends on details of temperature and pressure that are non relevant hither.) So the loss of that potential free energy leads to a loss of a few nanograms in mass, a quantity that is for all applied purposes unmeasurable.

But when analyzing nuclear reactions, the potential-free energy-equivalent mass becomes (barely) measurable, and, when methods of measuring atomic weights became sufficiently accurate in the 1910s and 1920s, it was noticed.

For example, a Radium atom has a mass (atomic weight) of 226.0254098 amu (atomic mass units). It decays by alpha decay into a Radon cantlet (222.0175777 amu) and a Helium atom (alpha particle, iv.0026033 amu.) The discrepancy is .0052288 amu. This is the potential-free energy-equivalent mass of the Radium atom. That is, .0052288 amu of the Radium atom's mass was this potential-energy-equivalent mass. Information technology disappeared when the potential energy was converted into kinetic free energy. The various conversion factors among amu, kilograms, Joules, and electron volts, forth with the conversion factor of ane.1110⁻¹⁷ given above, yields a potential energy loss of four.870596 MeV. This got converted into the kinetic energy of both the alpha particle and the recoiling Radon atom. Using the laws of conservation of Energy and of momentum, one can calculate the ratio of blastoff energy to recoil free energy; it is the same every bit the ratio of Radon cantlet mass to Helium atom mass—55.5 to i. Hence the recoil free energy of the Radon atom is expected to be most 0.0868 Mev, and the expected alpha particle kinetic free energy is four.784 MeV. This is the observed alpha particle energy.

Background Theory

The "lost" mass in radioactive decays and also in nuclear fusion can be explained using relativity and Einstein's famous equation, E=mc². From this equation, it is clear that the conversion cistron from earlier should exist equal to .

Application to the origins of the universe

The Law of Mass Conservation is believed by some to be in disharmonize with religious sensibilities, patently relating to the initial creation of the universe, or its ultimate fate. While the exact circumstances and causes of the "big blindside" are discussed by cosmologists and philosophers, the Law of Mass Conservation is accepted for everything in between.

See also

• Conservation of Free energy
• Conservation of momentum
• E=mc²

Notes

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Source: https://www.conservapedia.com/Law_of_the_conservation_of_mass

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