A solution of LiCl in water is 20.0 wt% LiCl. What is the mole fraction of LiCl?0.09600.4720.1064.44

mole fraction of LiCl = 0.096

Explanation:

Weight percentage -

weight percentage of A is given as, the weight of the substance A by weight of the total solution multiplied by 100.

i. e.

weight % A = weight of A / weight of solution * 100

GIven,

20.0 wt% LiCl

Now,

Assuming weight of solution = 100 g,

weight if LiCl = 20.0 g

Since,

Moles is denoted by given mass divided by the molecular mass,

Hence,

n = w / m

n = moles,

w = given mass,

m = molecular mass.

From the question,

molar mass of LiCl = 42.39 g/mol

moles of LiCl = mass / molar mass = 20.0 g / 42.39 g/mol = 0.472 mol

Since, solution = 100 g,

and,

Solution = solute + solvent

100g = 20g + solvent

Solvent = 80 g

mass of water = 80 g

water molecular mass = 18 g/mol

moles of water = 80g / 18 g/mol = 4.44 mol

Mole fraction -

It is the ratio of the moles of one of the component of the solution by the mole of the solution.

Total moles of the solution = moles of the solute + moles of solvent

Total moles of the solution = 0.472 mol + 4.44 mol = 4.92 mol

Now,

mole fraction of LiCl = moles of LiCl / total moles = 0.472 mol / 4.92

mole fraction of LiCl = 0.096