Chemistry
A compound X consists of 4.8% carbon and 95.2% bromine by mass.
(i) Determine the empirical formula of this compound working correct to one decimal place (C = 12; Br = 80)
(ii) If the vapour density of the compound is 252, what is the molecular formula of the compound?
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Answer
| Element | % composition | At. wt. | Relative no. of atoms | Simplest ratio |
|---|---|---|---|---|
| carbon | 4.8 | 12 | = 0.4 | = 1 |
| bromine | 95.2 | 80 | = 1.19 | = 2.9 = 3 |
Simplest ratio of whole numbers = C : Br = 1 : 3
Hence, empirical formula is CBr3
(ii) Empirical formula weight = 12 + 3(80) = 252 g
Molecular weight = 2 x V.D. = 2 x 252 = 504
Molecular formula = n[E.F.] = 2[CBr3] = C2Br6
∴ Molecular formula = C2Br6
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