Q13 / 180 · COMEDK 2023 (Evening Shift) · Chemistry
What is the mole fraction of solute in a $5 \mathrm{~m}$ aqueous solution?
- Correct answerA0.082
- B0.038
- C0.593
- D0.751
Solution
A $5 \text{ m}$ aqueous solution means $5$ moles of solute are dissolved in $1 \text{ kg}$ ($1000 \text{ g}$) of solvent (water).
The number of moles of water ($n_{solvent}$) is calculated as:
$n_{solvent} = \dfrac{1000 \text{ g}}{18 \text{ g/mol}} \approx 55.56 \text{ mol}$
The mole fraction of the solute ($x_{solute}$) is given by the ratio of moles of solute to the total number of moles in the solution:
$x_{solute} = \dfrac{n_{solute}}{n_{solute} + n_{solvent}}$
$x_{solute} = \dfrac{5}{5 + 55.56} = \dfrac{5}{60.56}$
$x_{solute} \approx 0.08256$
Answer: 0.082
The number of moles of water ($n_{solvent}$) is calculated as:
$n_{solvent} = \dfrac{1000 \text{ g}}{18 \text{ g/mol}} \approx 55.56 \text{ mol}$
The mole fraction of the solute ($x_{solute}$) is given by the ratio of moles of solute to the total number of moles in the solution:
$x_{solute} = \dfrac{n_{solute}}{n_{solute} + n_{solvent}}$
$x_{solute} = \dfrac{5}{5 + 55.56} = \dfrac{5}{60.56}$
$x_{solute} \approx 0.08256$
Answer: 0.082
Hence, the correct answer is option: 'A'.