Determine the Number of Representative Particles in Each Case

To determine the number of representative particles in a given number of moles, we use Avogadro’s number, which is approximately 6.022 x 10²³ particles/mol. A representative particle can be an atom, molecule, or formula unit, depending on the substance.

1. For 11.5 mol of Ag:

Silver (Ag) is a metal, and the representative particles are atoms. To find the number of atoms, we multiply the number of moles by Avogadro’s number:

Number of particles = 11.5 mol × 6.022 x 10²³ particles/mol = 69.2 x 10²³ atoms

2. For 18.0 mol of H₂O:

Water (H₂O) is a molecular compound, and the representative particles are molecules. We apply the same calculation:

Number of particles = 18.0 mol × 6.022 x 10²³ particles/mol = 108.4 x 10²³ molecules

3. For 0.150 mol of NaCl:

Sodium chloride (NaCl) is an ionic compound, and its representative particles are formula units. Using the same formula:

Number of particles = 0.150 mol × 6.022 x 10²³ particles/mol = 9.033 x 10²² formula units

In summary:

• 11.5 mol of Ag contains approximately 69.2 x 10²³ atoms.
• 18.0 mol of H₂O contains approximately 108.4 x 10²³ molecules.
• 0.150 mol of NaCl contains approximately 9.033 x 10²² formula units.