Answer:
[NaCl] = 0.14 M
[NaCl] = 0.14 m
Mole fraction of NaCl → 2.48×10⁻³
Explanation:
This is a problem of concentration.
0.8% w/w means that in 100 g of solution, we have 0.8 g of solute, in this case NaCl.
Let's determine the volume with the density.
Solution density = Solution mass / Solution volume
1.036 g/mL = 100 g / Solution volume
Solution volume = 100 g / 1.036 g/mL → 96.5 mL
Let's calculate molarity (mol/L)
We convert the mass to moles (mass / molar mass)
0.8 g / 58.45 g/mol = 0.0137 moles
We must convert the volume of solution to L.
Molarity is mol/L, moles of solute in L of solution.
96.5 mL . 1L/1000 mL = 0.0965 L
0.0137 mol / 0.0965 L = 0.14 M
Let's determine molality and mole fraction.
Molality are moles of solute in 1 kg of solvent (mol/kg)
Mass of solution = Mass of solute + Mass of solvent
100 g = 0.8 g + Mass of solvent
100 g - 0.8 g = Mass of solvent → 99.2 g
Then, we must convert the mass of solvent to kg
99.2 g . 1kg / 1000 g = 0.0992 kg
Molality: 0.0137 mol / 0.0992 kg → 0.14 m
Mole fraction → moles of solute / moles of solute + moles of solvent
Let's find out the moles of solvent ( mass / molar mass)
99.2g / 18 g/mol = 5.511 mol
Total moles = 5.511 + 0.0137 → 5.5247 moles
Mole fraction = 0.0137 / 5.5247 → 2.48×10⁻³
