to find the number of particles, you need to use Avogadro's number
6.02 x 10^23= 1 mol
As you can see, before we can convert to particles, we need moles. So let's first convert grams to moles using the molar mass (molecular weight) of the compound
molar mass of SrCO₃= 87.6 + 12.0 + (3 x 16.0)= 147.6 g/mol
53.79 g (1 mol/ 147.6 g)= 0.364 mol
now let's convert moles to particles using Avogadro's number
0.364 mol SrCO₃ (6.02x10^23/ 1 mol)= 2.19 x 10^23
