High School

An aqueous antifreeze solution is 40.0% ethylene glycol ([tex]C_2H_6O_2[/tex]) by mass. The density of the solution is 1.05 g/mL. Calculate the molality, molarity, and the mole fraction of the ethylene glycol.

a) Molality: 4.26 m, Molarity: 5.00 M, Mole fraction: 0.747
b) Molality: 5.00 m, Molarity: 4.26 M, Mole fraction: 0.747
c) Molality: 4.26 m, Molarity: 4.26 M, Mole fraction: 0.747
d) Molality: 5.00 m, Molarity: 5.00 M, Mole fraction: 0.747

Answer :

Final answer:

To find the molality, calculate the moles of the solute and convert the mass of the solvent to kilograms. Divide the moles of solute by the mass of solvent in kilograms. To find the molarity, calculate the moles of solute, and divide by the volume of the solution in liters. To find the mole fraction, calculate the moles of each component and divide the moles of the solute by the total moles of both components. None of the given options are correct.

Explanation:

To find the molality of the solution, we need to know the moles of the solute and the mass of the solvent in kilograms. First, we calculate the moles of ethylene glycol using the given mass and molar mass. Then, we convert the mass of water from grams to kilograms. Finally, we divide the moles of ethylene glycol by the mass of water in kilograms to get the molality.

Calculate the moles of ethylene glycol: 2220 g × (1 mol / 62.07 g) = 35.8 mol

Convert the mass of water to kilograms: 2000 g ÷ 1000 = 2 kg

Calculate the molality: 35.8 mol / 2 kg = 17.9 m

To find the molarity of the solution, we need to calculate the moles of ethylene glycol per liter of solution. We already have the moles of ethylene glycol (35.8 mol), and the total volume of the solution can be calculated using the density. Then, by dividing the moles of ethylene glycol by the volume of the solution in liters, we can find the molarity.

Calculate the total volume of the solution: 2000 g × (1 ml / 1.05 g) × (1 L / 1000 ml) = 1.904 L

Calculate the molarity: 35.8 mol / 1.904 L = 18.8 M

To find the mole fraction of ethylene glycol, we need to calculate the moles of each component (ethylene glycol and water) and then divide the moles of ethylene glycol by the total moles of both components.

Calculate the moles of water: 2000 g × (1 mol / 18.02 g) = 111 mol

Calculate the total moles: 35.8 mol + 111 mol = 146.8 mol

Calculate the mole fraction of ethylene glycol: 35.8 mol / 146.8 mol = 0.244

None of the given options are correct.