SOLUTIONS What is a solution? What does that mean? Possible to have any state dissolved in any other; however, most inorganic rxns which involve solutions have solid or gas dissolved in water, so our emphasis will be on aqueous solutions. Solution Composition [concentration] Mass % - mass solute x 100 mass solution Mole fraction of A = n A = χ A n A + n B Molality = mol solute kg solvent Molarity = L solution Normality = # equivalents L solution For acid-base, 1 eq = mass of A or B which produces 1 mol of H + or OH -. For redox 1 eq = quantity of oxid or red agent which will provide or accept 1 mol of e -.

 1) Explain how you would prepare 500. mL of a 0.33 M solution of sodium chloride.  2) Determine the molal concentration of a solution in which 320. grams of glucose C 6 H 12 O 6 are dissolved in 4000 grams of water.  3) If the solubility of Carbon Dioxide in water is.625g/L at 790. Torr and 25.0 degrees Celsius; what would be the solubility at constant temperature and 3.00 atm?  4) If water and ethanol mix in all proportions they are said to be?  If however water and oil don’t mix at any proportion they are said to be?

 Depend only on the number of solute particles present, not on the identity of the solute particles.  Among colligative properties are  Vapor pressure depression  Boiling point elevation  Freezing point depression otic pressure

 Vapor pressure is caused by solvent evaporation  Adding a non-volatile solute ALWAYS lowers the vapor pressure ◦ more solute = less solvent at surface = ↓ evaporation = ↓ vapor = ↓ vapor pressure  Amount of solute is the only thing that alters this property – colligative property ◦ 1 mol glucose  1 mol glucose ◦ 1 mol NaCl  1 mol Na + and 1 mol Cl - ◦ van’t hoff factor – mol of particles per mol of solute

KCl(aq) = K + (aq) + Cl - (aq) CuSO 4 (aq) = Cu +2 (aq) + SO 4 2- (aq) K 2 SO 4 (aq) = 2 K + (aq) + SO 4 2- (aq) K+K+ Cl - K Cl Cu +2 SO 4 2- Cu SO 4 K+K+ SO 4 2- K+K+ KK SO 4

 For something to boil the vapor pressure = atmospheric pressure.  Adding solute = ↓ vapor pressure = ↑ boiling point  Example – adding salt to water before cooking spaghetti noodles causes that water to boil at a hotter temperature, which leads to the noodles cooking faster

 During freezing, the particles of a solid take on an orderly pattern.  Adding solute disrupts this pattern, so even more energy must be removed for the solution to solidify.  Examples – applying salt to icy roads helps prevent the water from freezing and the use of antifreeze in vehicles.

 BPE/FPD = kmi  k = a different constant for each solvent = positive for BP (.512 kg 0 C/mol for H 2 O) = negative for FP (-1.86 kg 0 C/mol)  m = molality  i = van’t hoff factor

 What is the boiling point of a solution that contains 1.25 mol of CaCl 2 in mL of H 2 O?  What is the freezing point of 72.3 g of magnesium sulfate in 1350 mL of H 2 O  PRE-LAB CALCULATION: The freezing point for H 2 O is lowered to C when 3.90 g of a non-volatile molecular solid is dissolved in 475 g H 2 O. Calculate the molar mass of the substance.

 Two types: 1. Suspension - a mixture from which particles settle out -suspension differs from a solution because the particles of a suspension are much larger & do not stay suspended (> 1000 nm) - Ex. – muddy water, gravy 2. Colloid -a mixture containing intermediate-sized particles larger than those in solutions but smaller than those in a suspension ( nm) - Ex. – glue, paint, smoke, milk, fog

Medium / Phases Dispersed phase GasLiquidSolid Continuous medium Gas NONE (All gases are mutually miscible)miscible Liquid aerosol Examples: fog, mist, hair spraysaerosolfog misthair sprays Solid aerosol Examples: smoke, cloud, air particulatessmoke cloudair particulates Liquid Foam Foam Example: whipped cream, Shaving creamwhipped creamShaving cream Emulsion Emulsion Examples: milk, mayonnaise, hand creammilk mayonnaisehand cream Sol Sol Examples: pigmented ink, blood pigmented ink blood Solid Solid foam Examples: aerogel, styrofoam, pumiceaerogel styrofoampumice Gel Gel Examples: agar, gelatin, jellyagar gelatinjelly Solid sol Example: cranberry glasscranberry glass

 Solution ◦ Less than 1 nm  Colloid ◦ Between 1 nm and 1000 nm  Suspension ◦ Larger than 1000 nm

 The scattering of visible light by colloidal particles is called the Tyndall effect.  Good test to distinguish between a solution and a colloid.