How many moles of CaCO3 are there in an antacid tablet containing 0.520 g CaCO3? How many formula units of CaCO3 are in this tablet?

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

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