Answer :
Answer:
Empirical formula of ibuprofen : [tex]C_{13}H_{18}O_2[/tex]
Molecular formula of ibuprofen : [tex]C_{13}H_{18}O_2[/tex]
Explanation:
Let the empirical formula of ibuprofen be = [tex]C_xH_yO_z[/tex]
Considering 100 gram of ibuprofen with 75.69% C, 8.80% H, and 15.51% O.
Mass of carbon = [tex]100\times \frac{75.69}{100}=75.69 g[/tex]
Moles of carbon = [tex]\frac{75.69 g}{12 g/mol}=6.3075 mol[/tex]
Mass of hydrogen = [tex]100\times \frac{8.80 }{100}=8.80 g[/tex]
Moles of hydrogen = [tex]\frac{8.80 g}{1 g/mol}=8.80 mol[/tex]
Mass of oxygen = [tex]100\times \frac{15.51}{100}=15.51 g[/tex]
Moles of oxygen = [tex]\frac{15.51 g}{16 g/mol}=0.9694 mol[/tex]
For empirical formula, divide the lowest value of moles from each moles of element present in the compound.
Carbon = [tex]x=\frac{6.3075 mol}{0.9694 mol}=6.5[/tex]
Hydrogen = [tex]y=\frac{8.80 mol}{0.9694 mol}=9[/tex]
Oxygen = [tex]z=\frac{0.9694 mol}{0.9694 mol}=1[/tex]
Empirical formula of ibuprofen :
[tex]C_xH_yO_z=C_{6.5}H_9O_1=C_{13}H_{18}O_2[/tex]
Molecular mass = n × empirical mass
Empirical mass of ibuprofen= [tex]13\times 12 g/mol+18\times 1g/mol+2\times 16 g/mol=206 g/mol[/tex]
Molecular mass of ibuprofen = 206 g/mol
206 g/mol = n × 206 g/mol
n = 1
Molecular formula = [tex]C_{13\times n}H_{18\times n}O_{2\times n}[/tex]
Molecular formula of ibuprofen :
= [tex]C_{13\times 1}H_{18\times 1}O_{2\times 1}=C_{13}H_{18}O_2[/tex]