How many atoms are in 149 g of calcium?

Answer 1

atomic mass Ca = 40.08 g/mol

Find mols of Ca that you have:

149 g Ca x 1 mol Ca / 40.08 g = 3.718 mols Ca

Find the number of atoms in 3718 mols of Ca. Use Avogadro's number 6.02x10²³ atoms/mol:

3.718 mols Ca x 6.02x10²³ atoms/mol = 2.24x10²⁴ atoms (3 sig. figs.)