Question

Use the periodic table to determine how many atoms of phosphorus (P) are in a sample that has a mass of 172.90 g.

3.48 × 1021 atoms

1.97 × 1022 atoms

3.36 × 1024 atoms

1.04 × 1026 atoms

Answer 1

Atomic mass of P ≈ 30.97 g/mol.

Moles of P = 172.90 g / 30.97 g/mol = 5.583 mol.

Atoms = 5.583 mol × 6.022×10^23 atoms/mol = 3.36×10^24 atoms.

Answer: 3.36 × 10^24 atoms.