Extra How long is a line of 1 mole of sand grains, each 1 mm in length? ( to make sense of your answer keep in mind that the closest star is about 2 X 10 ¹³ km away from us; the center of the Milky Way galaxy is about 2 X10¹⁷ km away)

6.02 X 10²³ sand grains ( 10^-3 m/sand grain)(10^-3 km/m) = 6.02 X 10¹⁷ km ( wow; past the center of the galaxy)

Suppose you took a mole of water molecules and divided them into droplets as wide as the sand grains. Using the volume of a sphere = (4/3)(3.14)r³, the volume of a spherical droplet, 1 mm in diameter, is 5.23 X 10^-4 cm³, and each gram of water = 1 cm³. If you lined them up, what would their length be?

1 mole of water = 18 g = 18 ml = 18 cm³

18 cm³(droplet/ 5.23 X 10^-4 cm³) = 34417 droplets

34417 droplets(10^-3 m/droplet) = only 34 meters long!

What is to be learnt from all these calculations?

Molecules are extremely small compared to sand grains. An equal number is considered in both examples, and yet the length between the two is dramatically different.