Question

Suatu larutan urea terdiri atas 6gram urea(Mr=60) dan 70, 2 gram air(Mr=18). temtukan fraksi mol masing2 zat dalam campuran tersebut

Answer 1

⇒ mol urea = 0,1 mol
⇒ mol air = 0,1 mol
fraksi mol (X)

Answer 2

Zat terlarut = urea
zat pelarut = air

mol urea = massa/Mr = 6/60 = 0,1 mol
mol air = 70,2 / 18 = 3,9 mol

X urea = (mol urea) / (mol urea + mol air)
             = (0,1) / (0,1 + 3,9)
             = (0,1)/4
             = 0,025
X air = (mol air) / (mol air + mol urea)
             = (3,9) / (3,9 + 0,1)
             = (3,9)/4
             = 0,975