Jawabanmu

2014-08-08T22:24:13+07:00
MR urea : 60, MR H2)/air = 18
urea = 18% = 18 gram = \frac{180}{60} =3 mol
air = 100%-18%=82% = 82 gram =  \frac{82}{18} = 4,56 mol 

Xurea = Mol(urea) : ( Mol(urea) + Mol(air) ) = 3 : (4,56+3) = 0,39
X air = 1-X urea = 1-0.39 = 0,61
eh maap salah urea nya 18 gram = 18/60 = 0,3 mol
jadi Xurea nya = 0,3 : (4,56+0,3) = 0,06
Xair = 1-0,06 = 0,94