Mole fraction of NaOH is aquous sol 0.15
Find molarity of the solution, %w/w, if the density of solution is 1.25 g/ml
From the given mole fraction, we can say that there are 0.15 moles of NaOH per 1 mole solution (NaOH + H2O). Therefore, the moles of H2O alone is equal to
1 - 0.15 = 0.85 mol H2O
We first find the molarity. Molarity is the moles of solute per liter of solution. We now have the moles of solute (which is equal to 0.15 moles NaOH). Since we know the moles of NaOH and H2O, we can get from there the mass of the solution, and since the density is given, we can solve fore the volume.
We solve first the individual masses of NaOH and H2O by multiplying their respective # of moles by their molar mass (use periodic table to get the weight of each element then add them to get the molar mass):
NaOH: 23 + 16 + 1 = 40 g/mol
H2O: 2*1 + 16 = 18 g/mol
Total Mass of Solution:
0.15 * 40 + 0.85 * 18 = 21.3 g solution
Volume = mass/density
V = 21.3 / 1.25
V = 17.04 mL
in liters, V = 0.01704 L
Molarity = moles solute / L solution
= 0.15 mol NaOH / 0.01704 L
= 8.8 M
For the %w/w, we just divide the mass of solute by the total mass of solution. Since both are already known,
%w/w = (0.15 * 40) / 21.3 * 100
%w/w = 28 %
Hope this helps~ :)