A 0.675 solution of lactose (c12h22011) in water has a density of 1.04 g/mL.?

Question

What is the mole fraction of lactose in the solution? I keep coming up with .358, is that correct?

Answer 1

Wl + Ww = Wt
Wl = 0.675Wt
Wt/Ww = 1.04
n(l) = Wl/342.296
n(w) = Ww/18.016
mf(l) = n(l)/(n(l + n(w))
mf(l) = (Wl/342.296)/(Wl/342.296+ Ww/18.016)
mf(l) = 18.016*0.675Wt/(18.016*0.675Wt + 342.296*Wt/1.04)
mf(l) = 18.016*0.675/(18.016*0.675 + 342.296/1.04)
mf(l) = 0.035632

It seems we disagree by an order o magnitude. The difference in numerals is probably due to the atomic weights we chose to use.