Molar mas CaCO3 = 100.09 g/mole
To convert 0.520 g to moles, we can use dimensional analysis:
0.520 g x 1 mole/100.09 g = 0.005195 moles = 0.00520 moles (to 3 significant figures)
To find the number of formula units, we again can use dimensional analysis and the fact that there are 6.02x1023 formula units in 1 mole:
0.00520 moles CaCO3 x 6.02x1023 form.units/mole = 3.13x1021 formula units
