We are asked to **determine the volume in the beaker with the aqueous solution of NaCl when equilibrium is attained (i.e. assuming ideal behavior)**.

Recall the formula for **molarity**:

$\overline{){\mathbf{Molarity}}{\mathbf{\left(}}{\mathbf{M}}{\mathbf{\right)}}{\mathbf{=}}\frac{\mathbf{moles}\mathbf{}\mathbf{solute}\mathbf{}\mathbf{\left(}\mathbf{mol}\mathbf{\right)}}{\mathbf{litre}\mathbf{}\mathbf{solution}\mathbf{}\mathbf{\left(}\mathbf{L}\mathbf{\right)}}}$

At equilibrium

$\mathbf{molarity}\mathbf{}\mathbf{NaCl}\mathbf{=}\mathbf{molarity}\mathbf{}\mathbf{non}\mathbf{-}\mathbf{electrolyte}\mathbf{}\mathbf{solution}$

Let** x **be the volume transferred from the non-electrolyte solution to the NaCl solution, therefore:

Volume of non-electrolyte solution: 35-x

Volume of NaCl solution: 35+x

Two beakers are placed in a sealed box at 25 ^{o}C. One beaker contains 35.0 mL of a 5.5×10^{−2} M aqueous solution of a nonvolatile nonelectrolyte. The other beaker contains 35.0 mL of a 4.0×10^{−2} M aqueous solution of NaCl. The water vapor from the two solutions reaches equilibrium.

What is the volume in the beaker with the aqueous solution of NaCl when equilibrium is attained, assuming ideal behavior?