Even though molecules are extremely small, there is a great amount of space between them. Here are three activities which provide evidence of this:

a. Fill one 1-cup measuring cup with water and another with alcohol. Where do you think the level of the mixture will be when the two liquids are poured into a single 2-
cup measuring cup? When the water and the alcohol are poured together, the volume is visibly less than two cups.

What do you think happened?

Try mixing one large jar of walnuts with an identical jar filled with dried peas. When the walnuts and peas are poured together, the mixture will be considerably less than expected, because the peas fit in the spaces between the walnuts.

Imagine that the walnuts represent molecules of alcohol (the larger molecules), and the peas represent the water molecules (the smaller molecules).

b. Fill one 1-cup measuring cup graduated cylinder with water and another with cotton. What will happen when the water is added to the cotton?

Think about it a little, then slowly add the water to the cotton, a little at a time. (The cotton should not cause the water to overflow.)

How do you account for what happened?

c. Fill a glass to the brim with water. When not a single drop can be added without causing an overflow, slowly add sugar, a little bit at a time. (The water will still not
overflow.)

What are some of the reasons why the sugar water did not overflow?