Answer
The formula of bupropion is $C_{13}H_{18}ClNO$.
Work Step by Step
In a sample of 100 g of bupropion, there is 65.13 g of carbon, 7.57 g of
hydrogen, 14.79 g of chlorine, 5.84 g of nitrogen, and 6.67 g of
oxygen.
Let's now calculate the moles of each element present in the sample.
$n (C) = \frac{m(C)}{M(C)}=\frac{65.13}{12.01} $ mol $ =5.423 $ mol
$n (H) = \frac{m(H)}{M(H)}=\frac{7.57}{1.008} $ mol $ =7.510 $ mol
$n (Cl) = \frac{m(Cl)}{M(Cl)}=\frac{14.79}{35.45} $ mol $ =0.417 $ mol
$n (N) = \frac{m(N)}{M(N)}=\frac{5.84}{14.01} $ mol $ =0.417 $ mol
$n (O) = \frac{m(O)}{M(O)}=\frac{6.67}{16.00} $ mol $ =0.417 $ mol
Divide those numbers by the smallest one of them and round the result to a whole number.
$ N (C) = \frac{n(C)}{n(Cl)}=13$
$ N (H) = \frac{n(H)}{n(Cl)}=18$
$ N (Cl) = \frac{n(Cl)}{n(Cl)}=1$
$ N (N) = \frac{n(N)}{n(Cl)}=1$
$ N (O) = \frac{n(O)}{n(Cl)}=1$
The final formula is $C_{13}H_{18}ClNO$.
