Mole (unit)
From Simple English Wikipedia, the free encyclopedia
Mole is the SI unit of measurement used to measure the number of things, commonly atoms or molecules. One mole of something is equal to 6.0221415×10²³ atoms or molecules of it. We call this number Avogadro's number. We use this number because it is the number of carbon atoms in one gram of carbon-12, which is the most common isotope of carbon. We can measure anything in moles, but it is not very useful for most things because the numbers are so big. For example, one mole of grapefruit would be as big as the earth. One hydrogen gas molecule is made from two hydrogen atoms. Therefore, one mole of hydrogen gas is two moles of hydrogen atoms.
Because different molecules and atoms do not have the same mass, one mole of one thing does not weigh the same as one mole of something else. Atom and molecule mass is measured in u. One u is equal to one gram per mole. This means that if an atom has a mass of one u, one mole of this atom weighs one gram.
[edit] Example calculation:
A methane molecule is made from one carbon atom and four hydrogen atoms. Carbon has a mass of 12.011 u and hydrogen has a mass of 1.008 u. This means that the mass of one methane molecule is 12.011 u + (4*1.008u), or 16.043 u. This means that one mole of methane has a mass of 16.043 grams.
