An aqueous solution contains 8.7% NaCl by mass.

1. Calculate the molality of the solution.
2. Calculate the mole fraction of the solution.

assume 100 grams of the solution.

you have 8.7 g of NaCl, figure the moles
You have 91.3 g of water, figure the moles

calculate the mole fraction.

molality=molesNaCl/kgsolvent

and you have .1 kg solvent.

1.49 m

To calculate the molality and mole fraction of the solution, we need to know the molar mass of NaCl.

The molar mass of NaCl is 58.44 g/mol.

1. To calculate the molality of the solution, we need to first calculate the moles of NaCl present in the solution.

Given that the solution contains 8.7% NaCl by mass, we can assume we have 100g of the solution. Therefore, we have 8.7g of NaCl.

To convert grams to moles, we divide the mass of NaCl by its molar mass:

8.7 g NaCl ÷ 58.44 g/mol = 0.149 moles NaCl

Now, we need to find the mass of water in kilograms.

Since 100g is the total mass (8.7g NaCl + 91.3g water), the mass of water is:

91.3g ÷ 1000 = 0.0913 kg

Finally, we can calculate the molality by dividing the moles of NaCl by the mass of water in kilograms:

Molality (m) = Moles of solute ÷ Mass of solvent in kg
Molality = 0.149 mol ÷ 0.0913 kg ≈ 1.63 mol/kg

Therefore, the molality of the solution is approximately 1.63 mol/kg.

2. To calculate the mole fraction of the solution, we need to find the moles of NaCl and moles of water in the solution.

The moles of NaCl is already calculated as 0.149 mol.

To calculate the moles of water, we divide the mass of water by its molar mass:

91.3 g ÷ 18.015 g/mol = 5.07 mol

Now, we can calculate the mole fraction by dividing the moles of NaCl by the total moles of the solution (NaCl + water):

Mole fraction of NaCl = Moles of NaCl ÷ (Moles of NaCl + Moles of water)
Mole fraction of NaCl = 0.149 mol ÷ (0.149 mol + 5.07 mol) ≈ 0.028

Therefore, the mole fraction of NaCl in the solution is approximately 0.028.