High School

Determine the molality of a solution prepared by dissolving 4.77 g of cyclohexane ([tex]C_6H_{12}[/tex], 84.2 g/mol) in 97.6 g of benzene ([tex]C_6H_6[/tex], 78.1 g/mol).

A) 0.5 mol/kg
B) 1.0 mol/kg
C) 2.0 mol/kg
D) 3.0 mol/kg

Answer :

Final answer:

To determine the molality of the solution, we calculate the number of moles of cyclohexane and the mass of benzene in kilograms. Once we have these values, we can use the formula for molality to find the molality of the solution, which is approximately 0.581 mol/kg.

Explanation:

To determine the molality of a solution, we need to calculate the number of moles of solute (cyclohexane) and the mass of the solvent (benzene) in kilograms.

First, we calculate the moles of cyclohexane using its molar mass:

Moles of cyclohexane = mass of cyclohexane / molar mass of cyclohexane

Moles of cyclohexane = 4.77 g / 84.2 g/mol

= 0.0567 mol

Next, we convert the mass of benzene to kilograms:

Mass of benzene = 97.6 g

= 0.0976 kg

Finally, we calculate the molality using the formula:

Molality = moles of solute / mass of solvent (in kg)

Molality = 0.0567 mol / 0.0976 kg

= 0.581 mol/kg

Therefore, the molality of the solution is approximately 0.581 mol/kg.

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