The number of atoms in a given mass of a substance can be calculated using the concept of Avogadro's number and the molar mass of the substance.
The molar mass of gold (Au) is approximately 196.97 grams/mol. Avogadro's number is approximately 6.022 × 10^23 atoms/mol.
To calculate the number of atoms in 25.00 grams of gold, we can use the following formula:
Number of atoms = (Mass of substance / Molar mass) × Avogadro's number
Number of atoms = (25.00 g / 196.97 g/mol) × (6.022 × 10^23 atoms/mol)
Calculating this equation gives us:
Number of atoms = (0.1269 mol) × (6.022 × 10^23 atoms/mol)
Number of atoms = 7.63 × 10^22 atoms
Therefore, there are approximately 7.63 × 10^22 atoms in 25.00 grams of gold.