CHEM 1A Chapter Notes - Chapter 3: Limiting Reagent, Reagent, Molar Mass
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CHEM 1A Full Course Notes
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Chemical stoichiometry is the quantities of materials consumed and produced in chemical reactions. Ex: 12c is assigned a mass of exactly 12 atomic mass units (amu), and the masses of all other atoms are given relative to this standard. Atoms or molecules are passed into a beam of high-speed electrons. The most accurate method currently available for comparing the masses of atoms. The atomic number on the periodic table is the average of all the isotopes on earth for that element. For example, carbon-12 has a mass of 12. 01 because of the isotopes carbon-13 and carbon-14. Even though natural carbon does not contain a single atom with mass 12. 01, for stoichiometric purposes we consider carbon to be composed of only one type of atom with a mass of 12. 01. Also used to determine the isotopic composition of a natural. The number equal to the number of carbon atoms in exactly 12 grams of pure 12c.