Final answer:
To find the number of atoms in a 25.0g gold nugget, we calculate the moles using the gold atomic mass and multiply by Avogadro's number, resulting in approximately 7.64×10²21 gold atoms.
Step-by-step explanation:
To calculate the number of gold (Au) atoms in a 25.0g nugget of pure gold, we can use Avogadro's number and the atomic mass of gold. First, we find the number of moles of gold, then utilize Avogadro's number to get the total atoms.
The atomic mass of gold is approximately 196.97 g/mol. Therefore, the number of moles of gold in a 25.0 g nugget is calculated by dividing the mass by the atomic mass of gold:
Number of moles = 25.0 g / 196.97 g/mol = 0.1269 mol
Avogadro's number, which is 6.022×10²23 atoms per mole, is then used to find the number of atoms:
Number of Au atoms = 0.1269 mol × 6.022×10²23 atoms/mol
Number of Au atoms = 7.64×10²21 atoms of gold
Therefore, a 25.0g nugget of gold contains approximately 7.64x10²21 gold atoms.