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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`. |
Answer» 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` |
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