A polystryrene, having formula `Br_(3) C_(6) H_(2) (C_(8) H_(8))_(n)`, was perpared heating styrene with tribromobenzoyl peroxide in the absence of air. If it was found to contain 1.46% bromine by weight, find the value of `n`.

Explanation

Let the weigth of polystrene prepared be `100 g`
Therefore, the number of moles of `Br` in `100 g` of polystyrene
`(10.46)/(79.9) = 0.1309 mol`
From the formula of polystyrene, we have,
Number of mol `Br = 3 xx mol of Br_(3) C_(6) H_(2) (C_(8) H_(8))_(n)`
`0.139 = 3 xx ("Weight")/("Molecular Weight")`
`0.139 = (3 xx 100)/(314 + 104 n)`
`n = 19`