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, ite xxxx, 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, ite xxxx, 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, ite xxxx, and no units are necessary in the
answer.)

Solution
4.5(153 votes)

Answer

20.23 Explanation 1. Define molality formula Molality (m) is defined as m = \frac{\text{moles of solute}}{\text{kilograms of solvent}}. 2. Calculate moles of ethanol Assume 100 g of solution. 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 (solvent) 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{kilograms of water}}. Substitute values from Steps 2 and 3.

Explanation

1. Define molality formula<br /> Molality ($m$) is defined as $m = \frac{\text{moles of solute}}{\text{kilograms of solvent}}$.<br /><br />2. Calculate moles of ethanol<br /> Assume 100 g of solution. 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 (solvent)<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: $m = \frac{\text{moles of ethanol}}{\text{kilograms of water}}$. Substitute values from Steps 2 and 3.
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