Question

A polystyrne having formula Br₃C₆H₃ (C₃H₈ )n found to contain 10.46% of bromine by weight. Find the value of n. (At. wt. Br = 80) 

Answer 1

Let the wt of compound is 100 gm & molecular wt is M

Then moles of compound = 100/M

Moles of Br =100/M x 3

wt of Br = 100/M x 3 x 80 = 10.46

M = 2294.45 = 240 + 75 + 44 n , Hence n = 45