The mole fraction of a solute in one molal ethanolic solution would be

The mole fraction of a solute in one molal ethanolic solution would be
  1. 0.21
  2. 0.52
  3. 0.044
  4. 0.75

Solution

1 molal solution means 1 mol of solute in 1000 g or 1 kg of ethanol. Molecular weight of ethanol = 46.07 g/mol Number of moles of ethanol $\begin{aligned} & \qquad=\frac{\text { Weight of ethanol }}{\text { Molecular weight of ethanol }} \\ & =\frac{1000 \mathrm{~g}}{46.07 \mathrm{~g} / \mathrm{mol}} \\ & =21.70 \mathrm{~mol} \\ & \therefore \text { Mole fraction of solute }=\frac{1 \mathrm{~mol}}{1 \mathrm{~mol}+21.70 \mathrm{~mol}} \\ & =\frac{1 \mathrm{~mol}}{22.70 \mathrm{~mol}} \\ & =0.044\end{aligned}$ Hence, mole fraction of solute is 0.044.

Asked in: AP EAMCET 2021 (25 Aug Shift 2)

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