Terdapat 500 ml larutan glukosa 0,15 M,jika Mr glukosa =180 dan massa jenis larutan = 1,1 gram /ml.tentukan fraksi mol glukosa

Fraksi mol

Diketahui :
[glukosa] = 0,15 M
V lar.glukosa = 500 mL = 0,5 L
Mr glukosa = 180
mj lar.glukosa = 1,1 gram/mL

Ditanya :
X glukosa = ....?

n glukosa = M × V
= 0,15 M × 0,5 L
= 0,075 mol

m glukosa = n glukosa × Mr
= 0,075 mol × 180
= 13,5 gram

m lar.glukosa = mj × V
= 1,1 gr/mL × 500 mL
= 550 gram

m air = m lar.glukosa - m glukosa
= 550 gram - 13,5 gram
= 536,5 gram

Mr air = 2 Ar H + Ar O
= 2(1) + 16
= 18

n air = m air / Mr
= 536,5 gr / 18
= 29,8 mol

n total = n air + n glukosa
= 29,805 mol + 0,075 mol
= 29,880 mol

X glukosa = n glukosa / n total
= 0,075 mol / 29,880 mol
= 0,00251 = 2,51 × 10^-3