SOLVED

71) What is the molarity of a saturated solution of potassium sulfate if the solubility is 13 g per 100 g H2O at 25°C? The density of the solution is 1.1 g/mL A) 0.14 M B) 1.1 M C) 0.96 M D) 0.73 M E) 0.79 M 72) The solubility of ammonium permanganate is 7.90 g/100 mL of water. 29.0 grams of ammonium permanganate are placed in a container and 220 mL of water is added. The liquid is allowed to stand in contact with the solid until equilibrium is achieved and then the liquid is poured off. What is the weight of solid left? A) 17.4 g B) 79.0 g C) 7.90 g D) 11.6 g E) 29.0 g 73) A saturated solution of ammonium sulfate, (NH4)2SO4, in water at 30°C contains 78.0 g (NH4)2SO4 per 100.0 g H2O. What is the molality of this solution? A) 0.780 m B) 1.69 m C) 0.590 m D) 0.0590 m E) 5.90 m 74) The vapor pressures of pure propyl alcohol and isopropyl alcohol are 21.0 mmHg and 45.2 mmHg, respectively, at 25°C. Calculate the partial pressure of isopropyl alcohol above a solution in which the mole fraction of propyl alcohol is 0.250. A) 33.9 mmHg B) 11.3 mmHg C) 5.25 mmHg D) 15.8 mmHg 75) The concentration unit used in Raoult’s Law calculations is ________. A) mole fraction B) percent by weight C) molarity D) molality E) grams per L 76) If a solution containing 4 mols of A and 6 mols of B boils at 85°C and 1 atm of pressure, and the vapor pressure of pure A at 85°C is 500 mmHg, what is the vapor pressure of pure B at this temperature? A) 933 mmHg B) 336 mmHg C) 260 mmHg D) 576 mmHg E) 960 mmHg 77) Given that the vapor pressure of pure n-hexane and pure n-heptane at 25°C are 151.4 mmHg and 45.62 mmHg respectively, calculate the total vapor pressure above a solution containing only n-hexane and n-heptane in which the mole fraction of n-hexane is 0.600. A) 87.9 mmHg B) 197 mmHg C) 106 mmHg D) 109 mmHg E) 170 mmHg 78) The vapor pressures of pure hexane and pure heptane at 25°C are 151.4 mmHg and 45.62 mmHg respectively. A solution contains 0.800 mol fraction n-hexane and 0.200 mol fraction n-heptane. What is the composition of the vapor in equilibrium with this solution at 25°C? A) 80.0% hexane, 20.0% heptane B) 50.0% hexane, 50.0% heptane C) 77.0% hexane, 23.0% heptane D) 45.0% hexane, 55.0% heptane E) 93.0% hexane, 7.0% heptane 79) A mixture of benzene and toluene has a total vapor pressure at 25°C of 45.06 mmHg. What is the partial pressure of benzene in this solution? The vapor pressure of pure benzene and pure toluene at 25°C are 95.03 mmHg and 28.40 mmHg respectively. A) 0.7500 mmHg B) 23.76 mmHg C) 0.3217 mmHg D) 21.30 mmHg E) 16.66 mmHg 80) What is the correct value for the weight of Na3PO4 needed to make 100 mL of a 0.50 molar solution? A) 16.4 g B) 8.2 g C) 0.05 g D) 82 g E) 4.1 g