Chapter 8

What is meant by dynamic equilibrium? How does it differ from static equilibrium?

Suppose that you have collected \(1.0 \mathrm{~L}\) of humid air by passing it slowly through water at \(20^{\circ} \mathrm{C}\) and into a container. Estimate the mass of water vapor in the collected air, assuming that the air is saturated with water. \(\mathrm{Ar} 20^{\circ} \mathrm{C}\), the vapor pressure of water is \(17.5\) Torr.

Which would be the better solvent, water or benzene, for cach of the following: (a) \(\mathrm{KCl}\); (b) \(\mathrm{CCl}_{4}\), (c) \(\mathrm{CH}_{3} \mathrm{COOH}\) ?

Which would be the better solvent, \(\mathrm{H}_{2} \mathrm{O}\) or \(\mathrm{CCl}_{4}\), for each of the following: (a) \(\mathrm{NH}_{5} ;\) (b) \(\mathrm{HCl} ;\) (c) \(\mathrm{I}_{2}\) ?

The following groups are found in some organic molecules. Which are hydrophilic and which are hydrophobic: (a) \(-\mathrm{OH}_{;}\)(b) \(-\mathrm{CH}_{2} \mathrm{CH}_{3}\); (c) \(-\mathrm{CONH}_{2}\); (d) \(-\mathrm{Cl}\) ?

The carbon dioxide gas dissolved in a sample of water in a partially filled, sealed containcr has reached equilibrium with its partial pressure in the air above the solution. Explain what happens to the solubility of the \(\mathrm{CO}_{2}\) if (a) the partial pressure of the \(\mathrm{CO}_{2}\) gas is doubled by the addition of more \(\mathrm{CO}_{2} ;\) (b) the total pressure of the gas above the liquid is doubled by the addition of nitrogen.

The enthalpy of solution for ammonium nitrate in water is positive. (a) Does \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) dissolve endothermically or exothermically? (b) Write the chemical equation for the dissolving process. (c) Which is larger for \(\mathrm{NH}_{4} \mathrm{NO}_{3}\), the lattice enthalpy or the enthalpy of hydration?

A \(0.40-\mathrm{g}\) sample of a polypeptide dissolved in \(1.0 \mathrm{~L}\) of an aqueous solution at \(27^{\circ} \mathrm{C}\) has an osmotic pressure of \(3.74\) Torr. What is the molar mass of the polypeptide?

A \(0.10-\mathrm{g}\) sample of a polymer, dissolved in \(100 \mathrm{~mL}\). of toluene, had an osmotic pressure of \(5.4\) Torr at \(20^{\circ} \mathrm{C}\). What is the molar mass of the polymer?

A solution prepared by adding \(0.50 \mathrm{~g}\) of a polymer to enough toluene (an organic solvent) to make \(200 \mathrm{~mL}\). of solution had an osmotic pressure of \(0.582\) Torr at \(20^{\circ} \mathrm{C}\). What is the molar mass of the polymer?