QuestionJuly 31, 2025

What is the molality of ethanol (C_(2)H_(5)OH) in an aqueous solution that is 48.2% ethanol by mass? (Report your answer to two decimal places, i.e xx.xx, and no units are necessary in the answer.)

What is the molality of ethanol (C_(2)H_(5)OH) in an aqueous solution that is 48.2% ethanol by mass? (Report your answer to two decimal places, i.e xx.xx, and no units are necessary in the answer.)
What is the molality of ethanol (C_(2)H_(5)OH)
in an aqueous solution that is
48.2%  ethanol by
mass?
(Report your answer to two decimal places, i.e xx.xx, and no units are necessary in the
answer.)

Solution
4.6(246 votes)

Answer

20.14 Explanation 1. Define molality Molality (m) is defined as moles of solute per kilogram of solvent. **m = \frac{\text{moles of solute}}{\text{kg of solvent}}** 2. Calculate moles of ethanol Assume 100 g of solution for simplicity. Ethanol mass = 48.2\% of 100 g = 48.2 g. Molar mass of ethanol (C_{2}H_{5}OH) = 46.08 g/mol. Moles of ethanol = \frac{48.2}{46.08}. 3. Calculate mass of water Mass of water = Total mass - Ethanol mass = 100 g - 48.2 g = 51.8 g = 0.0518 kg. 4. Calculate molality Use the formula: m = \frac{\text{moles of ethanol}}{\text{kg of water}}. Substitute values from Steps 2 and 3.

Explanation

1. Define molality<br /> Molality ($m$) is defined as moles of solute per kilogram of solvent. **$m = \frac{\text{moles of solute}}{\text{kg of solvent}}$**<br /><br />2. Calculate moles of ethanol<br /> Assume 100 g of solution for simplicity. Ethanol mass = $48.2\%$ of 100 g = 48.2 g. Molar mass of ethanol ($C_{2}H_{5}OH$) = 46.08 g/mol. Moles of ethanol = $\frac{48.2}{46.08}$.<br /><br />3. Calculate mass of water<br /> Mass of water = Total mass - Ethanol mass = 100 g - 48.2 g = 51.8 g = 0.0518 kg.<br /><br />4. Calculate molality<br /> Use the formula: $m = \frac{\text{moles of ethanol}}{\text{kg of water}}$. Substitute values from Steps 2 and 3.
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