Answer:
The empirical formula is: [tex]CH_3[/tex]
Explanation:
In a sample of 100 g:
[tex]m_C=100g *0.8= 80g[/tex]
[tex]m_H=100g *0.2= 20g[/tex]
To determine the molecular formula you need to calculate the moles of each element. To do that the atomic weights are needed:
[tex]M_C=12g/mol[/tex]
[tex]M_H=1g/mol[/tex]
So, the moles of each one:
[tex]n_C=\frac{80g}{12g/mol}=6.66mol[/tex]
[tex]n_H=\frac{20g}{1g/mol}=20mol[/tex]
Now, you need to take this values to non-fractional numbers (keeping the ratio):
[tex]n_C=\frac{6.66mol}{6.66mol}=1[/tex]
[tex]n_H=\frac{20mol}{16.66mol}=3[/tex]
Therefore the empirical formula is: [tex]CH_3[/tex]
The molecular formula probably is a multiple of the empirical due to the carbon's valence.
