Question for Chemistry homework!! need help now!!!?

Question

Now if your lab partner needed 5.225 x 1020 molecules of Barium hydroxide (Ba(OH)2), how many milligrams would you need to weigh out?

Answer 1

The molar mass of Ba(OH)2 is 171.3 g/mol.

5.225 x 10^20 formula units Ba(OH)2 x (171.3 g / 1 mol ) x (1 mol / 6.02 x 10^23 formula units) = 0.149 g

0.149 g x (1000 mg / 1 g) = 149 mg