6.023*1023 Atoms One Mole

Same Number of Atoms

1 Mole of Helium Atoms

1 mole of Oxygen Atoms

15.9994 AMU

One mole of Oxygen Atoms 15.9994 g

4.022602 AMU

1 Mole of Helium Atoms 4.022602 g

Weight of 1 Mole of Helium Atoms

Weight of One mole of Oxygen Atoms

He

Weight of One Liter Balloon

O

Weight of One Liter Balloon

One mole is equal to 6.023*1023 atoms; therefore one mole of oxygen contains the same amount of atoms as one mole of helium. Furthermore, since one atom of helium has a mass of 4.022602 AMU, one mole of helium has a mass of 4.022602 grams, and since one atom of oxygen has a mass of 15.9994 AMU, one mole of oxygen has a mass of 15.9994 grams. This is due to Avogadroâ&#x20AC;&#x2122;s Law. Also, one liter of any gas at standard pressure is equal to 1/22.4 moles, so both one liter of helium and one liter of oxygen are equal to 1/22.4 moles. According to this, one liter of helium has the same amount of atoms as one liter of oxygen. All of this information means that a balloon filled with one liter of helium weighs significantly less than a balloon filled with one liter oxygen.

This demonstrates Avogadroâ&#x20AC;&#x2122;s Law, and is an everyday example.