What is the mole fraction of the solute in 2.5 molal aqueous solution?

Question

What is the mole fraction of the solute in 2.5 molal aqueous solution? (A)  0.043  (B)  0.053  (C)  0.063  (D)  0.073

Tardigrade Admin · Accepted Answer

2.5 molal solution means 2.5 moles of solute are present in 1000 mL solution (in aqueous solution) moles of water = (1000/18) = 55.55 mol ∴ Mole fraction of solute = (n1/n1 +n2) = (2.5/2.5 + 55.5) = (2.5/58.05) = 0.043

Q. What is the mole fraction of the solute in $2.5$ molal aqueous solution?

$0.043$

$0.053$

$0.063$

$0.073$

$2.5$ molal solution means $2.5$ moles of solute are present in $1000 m L$ solution (in aqueous solution) moles of water
$= \frac{1000}{18}$
$= 55.55 m o l$
$∴$ Mole fraction of solute
$= \frac{n _{1}}{n _{1} + n _{2}}$
$= \frac{2.5}{2.5 + 55.5}$
$= \frac{2.5}{58.05}$
$= 0.043$

Q. What is the mole fraction of the solute in 2.5 molal aqueous solution?

0.043

0.053

0.063

0.073