Answer:
0.468 m
Explanation:
From the question given above, the following data were obtained:
Mass of napthalalene (C₁₀H₈) = 30 g
Mass of toulene = 500 g
Molality =?
Next, we shall determine the number of mole in 30 g of C₁₀H₈. This can be obtained as follow:
Mass of C₁₀H₈ = 30 g
Molar mass of C₁₀H₈ = (12×10) + (8×1)
= 120 + 8
= 128 g/mol
Mole of C₁₀H₈ =?
Mole = mass / molar mass
Mole of C₁₀H₈ = 30 / 128
Mole of C₁₀H₈ = 0.234 mole
Next, we shall convert 500.0 g of toulene to Kg. This can be obtained as follow:
1000 g = 1 Kg
Therefore,
500 g = 500 g × 1 Kg / 1000 g
500 g = 0.5 Kg
Finally, we shall determine the molality of the solution. This can be obtained as follow:
Mole of solute (C₁₀H₈) = 0.234 mole
Mass of solvent (toulene) = 0.5 Kg
Molality =?
Molality = mole of solute / Kg of solvent
Molality = 0.234 / 0.5
Molality = 0.468 m
