Determine the mass in grams of 5.02 × 10²¹ atoms of barium. (The mass of one mole of barium is 137.33 g.)

Answer 1

Use dimensional analysis:

5.02x10²¹ atoms Ba x 1 mol Ba atoms/6.02x10²³ atoms x 137.33 g Ba/mol Ba = 1.15 g Ba (3 sig. figs.)