Respuesta :
The actual number of atoms of each element present in the molecule of the compound is represented by the formula known as molecular formula.
Molar mass of the unknown compound = 223.94 g/mol (given)
Mass of each element present in the unknown compound is determined as:
- Mass of carbon, [tex]C[/tex]:
[tex]\frac{32.18}{100}\times 223.94 = 72.06 g[/tex]
- Mass of hydrogen, [tex]H[/tex]:
[tex]\frac{4.5}{100}\times 223.94 = 10.08 g[/tex]
- Mass of chlorine, [tex]Cl[/tex]:
[tex]\frac{63.32}{100}\times 223.94 = 141.79 g[/tex]
Now, the number of each element in the unknown compound is determined by the formula:
[tex]number of moles = \frac{given mass}{molar mass}[/tex]
- Number of moles of [tex]C[/tex]:
[tex]number of moles = \frac{72.06}{12} = 6.005 mole\simeq 6 mole[/tex]
- Number of moles of [tex]H[/tex]:
[tex]number of moles = \frac{10.08}{1} = 10.08 mole\simeq 10 mole[/tex]
- Number of moles of [tex]Cl[/tex]
[tex]number of moles = \frac{141.79}{35.5} = 3.99 mole\simeq 4 mole[/tex]
Dividing each mole with the smallest number of mole, to determine the empirical formula:
[tex]C_{\frac{6}{4}}H_{\frac{10}{4}}Cl_{\frac{10}{4}}[/tex]
[tex]C_{1.5}H_{2.5}Cl_{1}[/tex]
Multiplying with 2 to convert the numbers in formula into a whole number:
So, the empirical formula is [tex]C_{3}H_{5}Cl_{2}[/tex].
Empirical mass = [tex]12\times 3+1\times 5+2\times 35.5 = 112 g/mol[/tex]
In order to determine the molecular formula:
n = [tex]\frac{molar mass}{empirical mass}[/tex]
n = [tex]\frac{223.94}{112} = 1.99 \simeq 2[/tex]
So, the molecular formula is:
[tex]2\times C_{3}H_{5}Cl_{2} = C_{6}H_{10}Cl_{4}[/tex]
