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Chemistry 1212 Problems on Solutions 1. The density of ethyl alcohol at 293 K is 0.79 g/cm3 and the density of chloroform at this temperature is 1.5 g/cm3. Calculate the mass percentage of chloroform in a solution prepared from equal volumes of ethyl alcohol and chloroform. 2. Calculate the mole fraction of ethylene glycol, C2H6O2, in a solution that is 74.5% by mass ethylene glycol in water. 3. The density of mercury is 13.6 g/ml at 273 K. A solution of silver in mercury, called an amalgam, is prepared from 30.0 ml of mercury and 2.34 grams of silver. Calculate the mole fraction of silver in the silver amalgam. 4. Calculate the molality of glycerin, C3H8O3, in a solution prepared from equimolar quanties of glycerin and water. 5. Calculate the molality of water in a solution that is 74.5% by mass ethylene glycol in water. 6. Calculate the quanties of water and acetone, C3H6O, necessary for the preparation of 120 grams of a solution that is 2.2 m acetone. 7. Calculate the molarity of a solution that contains 1.22 grams of hemoglobin (MW = 68300) in 165 ml of solution 8. The density of a solution of 18.0% lead nitrate (Pb(NO3)2) by mass in water is 1.18 g/ml. Calculate the molarity of lead nitrate. 9. A solution of 80.00% sulfuric acid by mass has a density of 1.727 g/ml. A volume of 50.00 ml of this solution is diluted with water until the volume of the solution is 75.00 ml. Calculate the molarity of sulfuric acid in the solution. 10. Calculate the volume of H2 at STP that is released when excess zinc is added to 36.2 ml of a 0.895 M solution of hydrochloric acid. 11. A solution of sugar is prepared by mixing 436 ml of 2.05 M sugar solution with 238 ml of 3.34 M sugar solution. Assume the volume of the resultant solution is the sum of the volumes of the two solutions. Calculate the molarity of sugar in the new solution. 12. A solution is prepared by mixing 631 ml of methanol with 501 ml of water. The molarity of methanol in the resulting solution is 14.29 M. The density of methanol at this temperature is 0.792 g/ml. Calculate the difference in volume between the solution and the total volume of the water and methanol that were mixed to prepare the solution. 13. Calculate the molality and mole fraction of ethanol in 25.4 proof wine at 293 K. The density of ethanol is 0.789 g/ml and the density of water is 0.998 g/ml at 293 K. Assume only two components in the water, water and alcohol. 14. The solubility of magnesium carbonate is 0.011 g/100 ml H2O. Calculate the molarity of magnesium carbonate in a saturated solution assuming no volume change upon formation of the solution. 15. A saturated solution of KMnO4 at 293 K is 0.40 M. Calculate the solubility of KMnO4 measured in grams per 100 ml of H2O assuming to volume change upon formation of the solution. 16. The density of a 22.0% solution of methanol in water by mass is 0.963 g/ml. Calculate the molarity of the solution. 17. Calculate the vapor pressure of water above a solution prepared from 18.22 grams of lactose, C12H22O11, and 81.46 grams of water at 338.0 K. The vapor pressure of pure water at this temperature is 0.2467 atm. 18. The density of a 3.742 M solution of glycerol, C3H8O3, in water at 298.0 K is 1.0770 g/ml. The vapor pressure of pure water at this temperature is 0.03126 atm. Calculate the vapor pressure of water above the solution. 19. The vapor pressure of pure benzene, C6H6, is 0.132 atm at 299 K. Calculate the mass of hexachlorobenzene, C6Cl6, that must be dissolved in 25 grams of benzene to lower its vapor pressure to 0.126 atm. 20. A solution is prepared from 26.7 grams of an unknown compound and 116.2 grams of acetone, C3H6O, at 313 K. The vapor pressure of pure acetone at this temperature is 0.526 atm and the vapor pressure of acetone above the solution is 0.501 atm. Calculate the molecular weight of the unknown compound. 21.* At 333 K the vapor pressure of benzene, C6H6, is 0.521 atm and the vapor pressure of toluene, C7H8, is 0.184 atm. A solution of equimolar amounts of these two liquids is prepared. Calculate the mole fraction of toluene in the vapor and the total vapor pressure above the solution. 22.* Two alcohols, isopropyl alcohol and propyl alcohol, have the same molecular formula, C3H8O. A solution of the two that is 2/3 by mass isopropyl alcohol has a vapor pressure of 0.110 atm at 313 K. A solution that is 1/3 by mass isopropyl alcohol has a vapor pressure of 0.089 atm at 313 K. Calculate the vapor pressure of each pure alcohol at 313 K. 23. Calculate the mass of sugar, C6H12O6, that must be dissolved in 1000 grams of ethanol to raise its boiling point 1.0 K. 24. A solution of 10.8 grams of an unknown substance in 101.2 grams of n-octane boils at 401.4 K. Calculate the molecular weight of the unknown. 25.* A solution of a non-volatile solute in water has a boiling point of 375.3 K. Calculate the vapor pressure of water above this solution at 338 K. 26. Calculate the freezing point of a 20.0% by mass ethylene glycol, C2H6O2, solution in water. 27. A solution of 0.358 grams of an unknown substance in 6.45 grams of camphor freezes at 446.8 K. Calculate the molecular weight of the unknown. kfp = 14.19 and MP = 176 oC for camphor. 28. A metal, M of atomic weight 96 reacts with fluorine to form a salt that can be represented as MFx. In order to determine x and therefore the formula of the salt, a boiling point elevation experiment is performed. A 9.18 gram sample of the salt is dissolved in 100 grams of water and the boiling point of the solution is found to be 374.38 K. Find the formula of the salt if BP(H2O) = 373.15 K. 29.* A solution contains 3.22 grams of HClO2 in 47.0 grams of water. The freezing point of the solution is 271.10 K. Calculate the fraction of HClO2 that undergoes dissociation to H+ and ClO2-. 30. Arginine vasopressin is a pituitary hormone. It helps regulate the amount of water in the blood by reducing the flow of urine from the kidneys. An aqueous solution containing 0.864 g of vasopressin in 100.0 ml of solution had an osmotic pressure at 25oC of 148 mm Hg. a) What is the molecular weight of the hormone? b) In problems #24 above, we saw that boiling point elevation was used to determine the molecular weight of an unknown. Why is that method not used here?

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