An aspirin tablet contains 325.0 mg of aspirin, which has the molecular formula, C9H8O4. How many molecules of aspirin are in the tablet?

1.08X10²¹ molecules aspirin are in the tablet

Explanation:

Molar mass of aspirin is 180.15 g/m (C₉H₈O₄)

This data means that 1 mol weighs 180.15 g so:

325 mg = 0.325 g

If 180.15 g are contained in 1 mol of aspirin

0.325 g (which is the weight from the tablet) are contained in ...

(0.325 g. 1m) / 180.15 g = 1.80x10⁻³ moles

1 mol has 6.02x10²³ molecules (NA)

1.80x10⁻³ moles are contained by ...

1.80x10⁻³. NA = 1.08X10²¹ molecules