VIEWS: 37 PAGES: 4 POSTED ON: 1/7/2010
Chapter 11 Properties of Solutions Definitions: Solute: Solvent: A __________________ is the result of mixing a solute in a solvent. A solution is a _____________________________. A suspension is ___________________. These will ________________ over time. The ______________________ effect determines if a mixture is a solution or a suspension. Light scatters through a suspension. Light does not scatter through a solution. Immiscible: Miscible: Units of concentration of a solution: 1] molarity 2] percent 3] parts per number (thousand, million, billion) 4] mole fraction 5] molality 6] normality For acids and bases: For oxidizing agents and reducing agents: 7] formality TTP 1] If the density of a 38% HCl solution is 1.19 g/mL, find its molarity, normality, mole fraction and molality 2] The density of a 99% acetic acid (vinegar) – HC2H3O2 is 1.05 g/mL, find M, N, m, χ. (molarity, normality, molality and mole fraction 3] Given a 1.25 M oxalic acid, H2C2O4, the density is 1.08 g/mL. Find percent solute by mass, molality, mole fraction and normality. Structural effects and solubility Recall oils are _______________ and water is _________________. Like dissolves _______. Polar solutes dissolve in water, but nonpolars dissolve in _________________ and ________. Soaps are : Hydrophobic: Hydrophilic: Vitamin A: Vitamin C: Pressure effects and solubility Henry’s Law: Equation: Temperature and solubility For gases: For ionic solids: (see graph p. 525) Saturated solutions: Unsaturated solutions: Supersaturated solutions: TTP: determine if the following solutions are saturated, supersaturated or unsaturated: o 1] 4.0 g of NaCl at 100 C in 10.0 g of water o 2] 12.0 g of KNO3 at 50 C in 20 g of water o 3] 14 g of NH4Cl at 40 C in 25 g of water o 4] 1.0 g of KCl at 30 C in 5 g of water o 5] 20 g of NaCl at 100 C in 50 g of water o 6] 0.14 g of Ce2(SO4)3 at 50 C in 15 g of water Find the concentration of Ni ions and Cl ions in a solution prepared by diluting 20.0 mL of a 1.00 M NiCl2 solution to 1.00 L Vapor pressure of solutions For an ideal solution: Adding a non-volatile solute _________________ the vapor pressure of the ________________. For an ideal solution: (equation) Graph: +2 -1 Negative deviations occur when: Positive deviations occur when: For exothermic reactions, there is a __________________ interaction between the __________. For endothermic reactions, there is a ________________ interaction between the ___________. Ideal solutions obey: Binary liquid mixtures: These refer to a mixture where both components are _______________. The overall vapor pressure is the pressure of the first component + the pressure of the second component. You have to factor in the mole fraction of each component. For an ideal solution: Ptotal = PA + PB where Ptotal is the total pressure. PA is the pressure of the first component, and PB is the pressure of the second component. The pressure of PA = ΧAPpure liquid A ; PB = ΧBPpure liquid B TTP#1: What is the total vapor pressure at 25 C of a mixture of 3.00 mol of benzene, C6H6, and o 2.00 mol of toluene, CH3C6H5. The vapor pressures of benzene and toluene at 25 C are 94.6 and 29.1 torr respectively. o TTP#2: When 8.05 g of an unknown compound X was dissolved in 100.0 g of benzene, the o vapor pressure of the benzene decreased from 100.0 torr to 94.8 torr at 26 C. What is a] the mole fraction and b] the molar mass of X? Colligative properties of solutions (for nonelectrolytes): These refer to: For freezing point: The physical presence of the solute ______________ the freezing point of the solvent. This is because: Equation: kf values can be found on p. 537 For boiling point: A solute causes the boiling point of the solvent to _____________. This is because: Equation: TTP 1] If 25.0 g of glucose, C6H12O6, is dissolved in 200.0 g of water, what is the temperature the solution will freeze? 2] At what temperature will the solution in #1 boil? 3] The kf value for benzene, C6H6, is 5.12. Benzene freezes at 5.5 C. If 10.0 of carbon tetrachloride is placed in 50.0 g of benzene, at what temperature will the solution freeze? o 4] Find the temperature that 1.00 g of benzaldehyde, C 6H5CHO, in 10.0 g of benzene will freeze. Finding the molar mass of compounds: 1] Find the molar mass of a compound that is a nonelectrolyte if 16.0 g of the compound when o added to 180.0 g of water freezes at -1.38 C. 2] Find the molar mass of a compound that is a nonelectrolytes if 5.00 g of the compound when o dissolved in 25.0 g of water boils at 102.00 C. Osmotic pressure Equation: 1] Find the molar mass of an unknown protein if 1.25 mg of the protein when added to water o makes 1.00 mL of solution. The osmotic pressure of the solution is 1.40 torr at 27.0 C. For electrolytes: New equations: Where i = __________ ____factor. The van’t Hoff factor is the number of particles that form when an electrolyte is in water. For NaCl, i = For Fe(NO3)3 i = However, the predicted changes in boiling point, freezing point and osmotic pressure are generally less than those you would predict. This is because of __________________. Since opposite charges ________________, the separate ions get together and act as if they were a single particle, rather than separate particles. The _______________ concentrated a solution, the greater the deviation from predicted change. The _____________ the i value, the greater the deviation. Problems: 1] Find the molar mass of an electrolyte that is made up of an alkali metal and a -1 o polyatomic anion if the solution freezes at -5.13 C when 15.0 g of the compound is added to 220.0 g of water. 2] Find the minimum osmotic pressure needed to get fresh water out of seawater at 25.0 C. The molarity of NaCl in seawater is 0.8214 M. o