Answer
About 2.778 $\times$ $10^{-3}$ mol of aspirin.
Work Step by Step
1. Calculate the molar mass of aspirin ($C_{9}H_{8}O_{4}$)
C: 12 * 9 = 108
H: 1 * 8 = 8
O: 16 * 4 = 64
108 + 8 + 64 = 180g/mol
2. Find the number of Mols in 0.5g of aspirin.
molar mass = $\frac{mass(g)}{mol}$
180 = $\frac{0.5}{mol}$
mol = $\frac{0.5}{180}$
mol = 0.002777...
