Moles of what? Remember that a mole is like a dozen. You can say "I have a dozen", but unless you specify what you have a DOZEN of, we may think you have 12 eggs, 12 legs, or perhaps 12 children. A mole is 6.022 x 10^23 of something. If I had a mole of eggs, I would have 6.022 x 10^23 eggs.

Usually the mole is used to measure the amount of atoms in a certain mass. Let's assume that you want to know how many moles of atoms there are in a cubic centimeter of water. Water, or H20, is a molecule made from two hydrogen and one oxygen atoms. A hydrogen atom weights around 1 gram per mole of atoms, and oxygen weighs around 16 grams per mole of atoms. There for each molecule of water weighs 2(1g/mol) + 16g/mol = 18g/mol. This means each mole (6.022 x 10^23) of molecules of water (containing 2 hydrogen atoms and one oxygen atom), the weight would be 18g.

Remember that there is one gram in one cubic centimeter of water. Divide 1 gram of water by 18 grams per mole of water molecules and you get .0556 moles of water molecules in one cubic centimeter (one milliliter) of water. Each molecule has 3 atoms, so multiply .0556 by three to give you .1667 moles of atoms per cubic centimeter of water.

Usually the mole is used to measure the amount of atoms in a certain mass. Let's assume that you want to know how many moles of atoms there are in a cubic centimeter of water. Water, or H20, is a molecule made from two hydrogen and one oxygen atoms. A hydrogen atom weights around 1 gram per mole of atoms, and oxygen weighs around 16 grams per mole of atoms. There for each molecule of water weighs 2(1g/mol) + 16g/mol = 18g/mol. This means each mole (6.022 x 10^23) of molecules of water (containing 2 hydrogen atoms and one oxygen atom), the weight would be 18g.

Remember that there is one gram in one cubic centimeter of water. Divide 1 gram of water by 18 grams per mole of water molecules and you get .0556 moles of water molecules in one cubic centimeter (one milliliter) of water. Each molecule has 3 atoms, so multiply .0556 by three to give you .1667 moles of atoms per cubic centimeter of water.