When dissolved in benzene, a compound `C_(38)H_(30)` partilly dissociates by the following equation:

`25.6 g` of `C_(38)H_(30)` is dissolved in `400 g` of benzene, the freezing point is lowered by `0.680^(@)C`. What percentage of `C_(38)H_(30)` molecules have dissociated? `(K_(f)=4.9)`

Explanation

`Delta T_b =I K_bm`
`i=(DeltaT_b)/(K_b(((g_B)/(M_b))/(g_A)xx1000))=(0.68)/(4.9(((25.6)/(486))/(400)xx1000))=1.0538`
Consider : `{:(C_(38)H_(30), hArr ,2 c_(19)H_(15)),(1-x,"",2x):}`
Total moles = 1-x+2x=1+x
`i=("Total Moles")/("Initial Moles") =(1+x)/1 rArr rArr 1.0538 =(1+x)/1 rArr x=0.0538 rArr % ` age dissociation = 5.38 %