A polystyrene, having the formula Br_(3)C_(6)H_(3)(C_(3)H_(8))_(n),was prepared by heating styrene with tribromobenzoyl peroxide in the absence of air. If it was found to contain 10.46% bromine by weight, find the value of n.

A polystyrene, having the formula Br_(3)C_(6)H_(3)(C_(3)H_(8))_(n),was

1.	A polystyrene, having the formula Br_(3)C_(6)H_(3)(C_(3)H_(8))_(n),was prepared by heating styrene with tribromobenzoyl peroxide in the absence of air. If it was found to contain 10.46% bromine by weight, find the value of n.
Answer» Solution :Let the weight of polystyrene PREPARED be 100 G `therefore` no. of moels of Br in 100 g of polystyrene `=(10.46)/79.9 = 0.1309` From the formula of polystyrene, we have no. of moles of Br = `3 xx` moles of `Br_(2)C_(6)H_(3)(C_(3)H_(8))_(n)` or `0.1309 = 3 xx (WT)/("mol. wt") = (3 xx 100)/(314.7 + 44 n)` `therefore n = 44.9 = 45`