How many atoms are in 20 grams of aluminum

4.5 × 10²³ number of atoms Al

Explanation:

Given data:

Mass of Al = 20 g

Number of atoms of Al = ?

Solution:

The given problem will solve by using Avogadro number.

'It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance" .The number 6.022 × 10²³ is called Avogadro number.

We will calculate  the number of moles of Al first:

Number of moles = mass/molar mass

Number of moles = 20 g/ 27 g/mol

Number of moles = 0.74 mol

1 mole = 6.022 × 10²³ number of atoms

0.74 mol ×  6.022 × 10²³ number of atoms / 1 mol

4.5 × 10²³ number of atoms Al