How many Li atoms are in 4.5 moles of Li?

The solution to this problem is actually very, very simple.

To find the number of atoms in a given number of moles, we simply multiply by Avogadro's constant.

The value of Avogadro's constant is 6.022 x 10²³

Number of Li atoms = moles x Avogadro's constant

Number of Li atoms = 4.5 x 6.022 x 10²³

Number of Li atoms = 2.7099 x 10²⁴

Number of Li atoms = 2.71 x