If you had to count out a 1,000 pennies, it would take a while, but it would be possible because you can actually see them. But, what if you had to count out 1000 or even 1,000,000 atoms? It would be impossible because atoms are very small! In fact, there is actually a unit of measure used for counting very large numbers of very small things. An activity that you can do to better understand this idea is on the following page: Activity#3: Counting By Weighing.
This unit is called the mole (also abbreviated mol). The number of things in one mole is:
6.02x10^23 which is also known as Avogadro's Constant.
Let's think about the size of this number. What if we had 6.02x10^23 sheets of paper.....how tall do you think this stack would be?
Surprisingly, it would reach the distance from Earth to the sun more than a million times! Yet, we cannot even compare an atom to the thickness of a piece of paper because an atom is much smaller.
Now that we know how small atoms, are it is understandable why moles to describe the amount of gas particles within a specific container.
One of the many misconceptions that students have about gases such as those in the Students' Ideas page is that they believe that gases do not weigh anything. In other words, gases do not have a total mass. Yet, we know that if we have a lot of gas particles, they may be light or heavy, but they do have mass! As a result, we usually convert mass to moles because moles is a unit that we can use to discuss the quantity of a gas.
Molar volume of a gas is the amount of space that a mole of gas occupies at a pressure of at one atmosphere and a temperature of 0.00 degrees Celsius. Therefore, molar volume is another direct measurement that we can use to solve stoichiometry problems.
A demonstration is located in the lessons page that allows the students to visualize molar volume is below: