Question

How many atoms of gold (Au,196.97 g/mol) are in a gold nugget with a mass of 4.259?

Answer 1

Mass of gold nugget = 4.259 g

Calculating the moles of gold from mass and molar mass:

$4.259 g Au * \frac{1 mol Au}{196.97 g Au} = 0.0216 mol Au$

Calculating the atoms of Au:

$0.0216 mol Au * \frac{6.022 * 10^{23} atoms Au}{1 mol Au} = 1.3*10^{22} atoms Au$

Therefore, $1.3 * 10^{22} atoms Au$ are present in a gold nugget with a mass of 4.259 g.