1. Avogadro's Number

* Avogadro's number tells us the number of particles (atoms, molecules, etc.) in one mole of a substance. It's a huge number: 6.022 x 10²³ particles/mol.

2. Calculation

* Start with the given moles: 0.45 mol S

* Multiply by Avogadro's number: 0.45 mol S * (6.022 x 10²³ atoms/mol)

* The 'mol' units cancel out, leaving you with atoms: 2.71 x 10²³ atoms of sulfur

Therefore, there are approximately 2.71 x 10²³ sulfur atoms in 0.45 mol of sulfur.