You can find 1) how many moles of aspirin are in the tablet, and 2) how many molecules
of aspirin are in the tablet
1) Formula: number of moles = mass in grams / molar mass
Molar mass of C9H8O4:
9*12.0g/mol + 8*1.0 g/mol + 4*16.0g/mol = 180 g/mol
mass of aspirin = 75.0 mg = 0,075 g
=> number of moles of aspirin = 0,075 g / 180 g/mol = 0.0004167 moles
=> Answer 1) 0.000417 moles of aspirin
2) number of molecules = number of moles * Avogadro's number =>
number of molecules = 0,000417 moles * 6.022 * 10^23 molecules / moles =
= 2.51 * 10^20 molecules.
Answer 2: 2.51 * 10^20 molecules
