Law of conservation of matter
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- Further information: law of conservation of mass
The Law of Conservation of Matter states that matter cannot be created or destroyed, only redistrubuted. In chemistry, it is represented by the fact that the sum of the masses of the reactants are equal to the sum of the products formed in a chemical reaction.[1]
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[edit] What Is Matter?
The difficulty in stating this law in terms of the word "matter" is that "matter" is not a well-defined word. Most definitions of matter require that it be comprised of ordinary fermionic matter, which is composed of fermionic particles such as neutrons, protons, electrons and positrons. Most definitions of "matter" include neither electromagnetic radiation (such as light or gamma rays) nor do not include forms of potential energy associated with static nuclear or electromagnetic fields. The problem, however, is that scientists now know that such fields represent an appreciable percentage of the mass of ordinary objects, and even of particles themselves when they are compound particles (i.e., hadrons). Moreover, the kinetic energy of particles in ordinary objects (such as the kinetic energy of atoms represented in heat, but also the kinetic energy of subatomic particles) contributes to the "mass" of objects, even though such energies are also not usually considered to be "matter."
[edit] Atoms
According to atomic theory, one could use the number of atoms, not mass, as a measure of matter.
This way, the Law can expressed as a stoichometric balance, which is:
The number of atoms of a particular element in the reactants must equal the number of those atoms in the products.
In a chemical change, there is no increase or decrease in the quantity of matter.
It is therefore practical to assume that the total energy gained by a loss of m, matter, is the product of m and the universal constant c, the speed of light, about or 3×108 m/s.
Even in nuclear chemistry, whenever matter is completely destroyed, it is always matter in the sense of fermionic particles encountering their antiparticles. (For example, positrons may be created and destroyed when they encounter electrons.) In most nuclear reactions, the actual "mass" which is converted to heat and light does not represent any particular type of particle, but is only the mass of static fields associated with particles in the nucleus. Exceptions involve the production of antimatter particles, which can be annihilated completely, with the associated production of electromagnetic radiation only.
[edit] Moles
The weight of each item in the experiment is measured in moles. The difficult part of the experiment is tranfering grams, liters, etc. into mole form. Once the substances have been properly wieghed and written down, the experiment is performed. After, the molecules of each substance are found in the result, and are carefully weighed. If the experiment is done properly, the molar mass should be exactly the same.
