Final answer:
The mass of a pure gold coin containing 0.140 mol of gold is calculated by multiplying the number of moles by the molar mass of gold (196.97 g/mol), resulting in a mass of 27.576 grams.
Step-by-step explanation:
To calculate the mass of a pure gold coin that contains 0.140 mol of gold, we use the concept of molar mass. The molar mass of gold (Au) is 196.97 g/mol, which means that one mole of gold has a mass of 196.97 grams. Therefore, to find the mass of 0.140 mol of gold, we multiply the number of moles by the molar mass of gold:
Mass = Number of moles × Molar mass of gold
Mass = 0.140 mol × 196.97 g/mol
Mass = 27.576 g
Thus, the mass of the gold coin is 27.576 grams.