Question

how many molecules of aspirin (molar mass=180u)are present in 50mg tablet?

Answer 1

Molar mass of aspirin (C₉H₈O₄)= 180 u
Mass of aspirin= 50 mg= 0.05g
Number of moles,n=
$\frac{Mass}{Molarmass}$
Number of molecules= n x 6.023 x 10²³
$\mathrm{n}=\frac{0.05}{180}=0.00027$
Number of molecules= 0.00027 x 6.023 x 10²³
=0.0016262 x 10²³ or 1.6262 x 10²⁶ molecules