When water and methanol, \(\mathrm{CH}_{3} \mathrm{OH}(\mathrm{l}),\) are mixed,
the total volume of the resulting solution is not equal to the sum of the pure
liquid volumes. (Refer to Exercise 99 for an explanation.) When \(72.061
\mathrm{g} \mathrm{H}_{2} \mathrm{O}\) and \(192.25 \mathrm{g}\) \(\mathrm{CH}_{3}
\mathrm{OH}\) are mixed at \(25^{\circ} \mathrm{C},\) the resulting solution has
a density of \(0.86070 \mathrm{g} / \mathrm{mL} .\) At \(25^{\circ} \mathrm{C},\)
the densities of water and methanol are \(0.99705 \mathrm{g} / \mathrm{mL}\) and
\(0.78706\) \(\mathrm{g} / \mathrm{mL},\) respectively.
(a) Calculate the volumes of the pure liquid samples and the solution, and
show that the pure liquid volumes are not additive. [ Hint: Although the
volumes are not additive, the masses are.]
(b) Calculate the molarity of \(\mathrm{CH}_{3} \mathrm{OH}\) in this solution.