Problem 47
Four solutions of \(\mathrm{K}_{2} \mathrm{SO}_{4}\) with the concentrations \(0.1 \mathrm{~m}, 0.01 \mathrm{~m}, 0.001 \mathrm{~m}\) and \(0.0001 \mathrm{~m}\) are available. The maximum value of colligative property corresponds to : (a) \(0.0001 \mathrm{~m}\) solution (b) \(0.001 \mathrm{~m}\) solution (c) \(0.01 \mathrm{~m}\) solution (d) \(0.1 \mathrm{~m}\) solution
Problem 51
Chloroform, \(\mathrm{CHCl}_{3}\), boils at \(61.7^{\circ} \mathrm{C}\). If the \(K_{b}\) for chloroform is \(3.63^{\circ} \mathrm{C} / \mathrm{molal}\), what is the boiling point of a solution of \(15.0 \mathrm{~kg}\) of \(\mathrm{CHCl}_{3}\) and \(0.616 \mathrm{~kg}\) of acenaphthalene, \(\mathrm{C}_{12} \mathrm{H}_{10} ?\) (a) \(61.9\) (b) \(62.0\) (c) \(52.2\) (d) \(62.67\)
Problem 53
A solution of \(0.640 \mathrm{~g}\) of azulene in \(100.0 \mathrm{~g}\) of benzene boils at \(80.23^{\circ} \mathrm{C}\). The boiling point of benzene is \(80.10^{\circ} \mathrm{C}\); the \(K_{b}\) is \(2.53^{\circ} \mathrm{C} /\) molal. What is the molecular weight of azulene? (a) 108 (b) 99 (c) 125 (d) 134
Problem 54
One molal solution of a carboxylic acid in benzene shows the elevation of boiling point of \(1.518 \mathrm{~K}\). The degree of association for dimerization of the acid in benzene is \(\left(K_{b}\right.\) for benzene \(\left.=2.53 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right):\) (a) \(60 \%\) (b) \(70 \%\) (c) \(75 \%\) (d) \(80 \%\)
Problem 56
Which one of the following aqueous solutions will exhibit highest boiling point: (a) \(0.015 \mathrm{M}\) urea (b) \(0.01 \mathrm{M} \mathrm{KNO}_{3}\) (c) \(0.10 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}\) (d) \(0.015 \mathrm{M}\) glucose
Problem 59
When a solution containing non-volatile solute freezes, which equilibrium would exist? (a) solid solvent \(\rightleftharpoons\) liquid solvent (b) solid solute \(\rightleftharpoons\) liquid solution (c) solid solute \(\rightleftharpoons\) liquid solvent (d) solid solvent \rightleftharpoons liquid solution
Problem 60
Bromoform has a normal freezing point of \(7.734^{\circ} \mathrm{C} / \mathrm{m}\) and it's \(K_{f}=14.4^{\circ} \mathrm{C} / \mathrm{m}\). A solution of \(2.60 \mathrm{~g}\) of an unknown in \(100 \mathrm{~g}\) of bromoform freezes at \(5.43^{\circ} \mathrm{C}\). What is the molecular weight of the unknown? (a) \(16.25\) (b) \(162.5\) (c) 100 (d) none of these
Problem 61
\(\mathrm{C}_{6} \mathrm{H}_{6}\) freezes at \(5.5^{\circ} \mathrm{C}\). At what temperature will a solution of \(10.44 \mathrm{~g}\) of \(\mathrm{C}_{4} \mathrm{H}_{10}\) in \(200 \mathrm{~g}\) of \(\mathrm{C}_{6} \mathrm{H}_{6}\) freeze? \(K_{f}\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)=5.12^{\circ} \mathrm{C} / \mathrm{m}\) (a) \(4.608^{\circ} \mathrm{C}\) (b) \(0.892^{\circ} \mathrm{C}\) (c) \(5.5^{\circ} \mathrm{C}\) (d) none of these
Problem 63
The freezing point of a solution of \(2.40 \mathrm{~g}\) of biphenyl \(\left(\mathrm{C}_{12} \mathrm{H}_{10}\right)\) in \(75.0 \mathrm{~g}\) of benzene \(\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)\) is \(4.40^{\circ} \mathrm{C}\). The normal freezing point of benzene is \(5.50^{\circ} \mathrm{C}\). What is the molal freezing point constant \(\left({ }^{\circ} \mathrm{C} / \mathrm{m}\right)\) for benzene? (a) \(-5.3\) (b) \(-5.1\) (c) \(-4.6\) (d) \(-4.8\)
Problem 66
Freezing point of a solution is smaller than that point of a solvent. It is due to : (a) \(\Delta H\) of solution and solvent is almost identical since intermolecular forces between solvent molecules are involved (b) \(\Delta S\) of solution (between solution and solid) is larger than that of the \(\Delta S\) of solvent (between solvent and solid) (c) \(\Delta S\) of the solution is smaller than that of the solvent (d) \(\Delta H\) of the solution is much higher than of solvent but \(\Delta S\) of solution is smaller than that of the solvent
