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.

Explanation

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`