# Avogadro's Number

The number of items in a sample of a substance which is equal to the number of atoms or molecules in a sample of an ideal gas which is at standard temperature and pressure. It is equal to about N = 6.022045x10^{23} mol^{-1}

### How big is Avogadro's Number?

- If we were able to count atoms at the rate of 1.4 million per second, it would take the age of the universe (about 13.7 billion years) to count the atoms in one mole (1.4x10
^{6}x 31.5x10^{6}x 13.7x10^{9}~ 6x10^{23}). - The number of popcorn kernels needed to cover the United States to a depth of nine miles.
- The number of cupfuls of water in the Pacific Ocean.
- The number of soft drink cans that would, evenly stacked, cover the Earth to a depth of 200 miles.

### Reference

Bill Bryson "A Short History of Nearly Everything"

**See also: **Avogadro, Armedeo, Boltzmann′s Constant, Physical Constants.