From the periodic table:
mass of hydrogen = 1 grams
mass of oxygen = 16 grams
mass of carbon = 12 grams
This means that:
mass of one mole of aspirin = 9(12) + 8(1) + 4(16) = 180 grams
number of moles can be calculated using the following rule:
number of moles = mass / molar mass
number of moles = 0.4 / 180 = 2.223 x 10^-3 moles
