Answer:
Empirical formula (which matches the molecular formula) is = PbC₈H₂₀
Explanation:
Our sample: 60 g of tetraethyl lead
In order to determine the compound empirical formula we need the centesimal composition:
(Mass of element / Total mass) . 100 =
(38.43 g lead / 60g ) . 100 = 64.05%
(17.83 g C / 60g) . 100 = 29.72%
(3.74 g H / 60g) . 100 = 6.23 %
These % are the mass of the elements in 100 g of compound. Let's find out the moles of them:
64.05 g / 207.2 g/mol = 0.309 moles
29.72 g / 12 g/mol = 2.48 moles
6.23 g/ 1 g/mol = 6.23 moles
Next, we divide the moles, by the lowest value of them (0.309)
0.309 / 0.309 = 1 mol Pb
2.48 / 0.309 = 8 mol C
6.23 / 0.309 = 20 mol H
There, we have our formula PbC₈H₂₀
