Here's how to calculate the number of atoms in 0.5 moles of Argon (Ar):

Key Concept: Avogadro's Number

Avogadro's number tells us the number of particles (atoms, molecules, etc.) in one mole of a substance. It's approximately:

* 6.022 x 10²³ particles/mole

Calculation:

1. Start with the given moles: 0.5 moles of Ar

2. Multiply by Avogadro's number: 0.5 moles * (6.022 x 10²³ atoms/mole)

3. Result: 3.011 x 10²³ atoms of Ar

Therefore, there are approximately 3.011 x 10²³ atoms in 0.5 moles of Argon.