Pada suhu tertentu sebanyak 3,6 gram urea dilarutkan kedalam 900 gram air jika tekanan uap air 17,54 mmhg tentukan penurunan tekanan uap dan tekanan uap larutan

wt = 3,6 gram (Mr = 60 gram)
wp = 900 gram (Mr = 18 gram)
P° = 17,54 mmHg
ΔP = ..................................?
P = ...................................?


nt = wt/Mr
    = 3,6/60
    = 0,06 mol
np = wp/Mr
     = 900/18
     = 50 mol

Xt = nt/(nt+np)
     = 0,06/(0,06+50)
     = 0,06/50,06
     = 0,012
Xp = 1 - Xt
     = 1 - 0,012
     = 0,988

P = Xp.P°
   = 0,988 x 17,54
   = 17,33 mmHg

ΔP = P° - P
      = 17,54 - 17,33
      = 0,21 mmHg