91Ó°ÊÓ

Acetic acid is a weak acid that ionizes in solution as follows: $$ \mathrm{CH}_{3} \mathrm{COOH}(a q) \rightleftharpoons \mathrm{CH}_{3} \mathrm{COO}^{-}(a q)+\mathrm{H}^{+}(a q) $$ If the freezing point of a \(0.106 \mathrm{~m} \mathrm{CH}_{3} \mathrm{COOH}\) solution is \(-0.203^{\circ} \mathrm{C},\) calculate the percent of the acid that has undergone ionization.

For ideal solutions, the volumes are additive. This means that if \(5 \mathrm{~mL}\) of \(\mathrm{A}\) and \(5 \mathrm{~mL}\) of \(\mathrm{B}\) form an ideal solution, the volume of the solution is \(10 \mathrm{~mL}\). Provide a molecular interpretation for this observation. When \(500 \mathrm{~mL}\) of ethanol \(\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)\) are mixed with \(500 \mathrm{~mL}\) of water, the final volume is less than \(1000 \mathrm{~mL}\) Why?

A mixture of liquids \(A\) and \(B\) exhibits ideal behavior. At \(84^{\circ} \mathrm{C},\) the total vapor pressure of a solution containing 1.2 moles of \(A\) and 2,3 moles of \(B\) is 331 \(\mathrm{mmHg}\). Upon the addition of another mole of \(\mathrm{B}\) to the solution, the vapor pressure increases to 347 \(\mathrm{mmHg}\). Calculate the vapor pressures of pure \(\mathrm{A}\) and \(\mathrm{B}\) at \(84^{\circ} \mathrm{C}\)

Using Henry's law and the ideal gas equation to prove the statement that the volume of a gas that dissolves in a given amount of solvent is independent of the pressure of the gas. (Hint: Henry's law can be modified as \(n=k P\), where \(n\) is the number of moles of the gas dissolved in the solvent.)