CHM 113 Chapter Notes - Chapter 10: Carbon-12, Unified Atomic Mass Unit, Molar Mass
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You are given the number of atoms of zinc and must nd the equivalent number of moles. If you compare 4. 50 1024 atoms zn with 6. 02 10 , the number of atoms in 1 mol, you can predict that the answer should be less than. 10 mol: solve for the unknown (cid:12254) Use a conversion factor the inverse of avogadro"s number that relates moles to atoms: evaluate the answer (cid:12254) Both the number of zn atoms and avogadro"s number have three signi cant. Therefore, the answer is expressed correctly with three digits. The answer is less than 10 mol, as predicted, and has the correct unit, moles. The mole is a unit used to count particles of matter indirectly. One mole of a pure substance contains avogadro"s number of representative particles. Representative particles include atoms, ions, molecules, formula units, electrons, and other similar particles. One mole of carbon-12 atoms has a mass of exactly 12 g.
