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SOLUTIONS

SOLUTIONS. Chemistry 21A Dr. Dragan Marinkovic. SOLUTIONS.

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SOLUTIONS

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  1. SOLUTIONS Chemistry 21A Dr. Dragan Marinkovic

  2. SOLUTIONS Asolutionis a homogeneous mixture of asolute and a solvent. Solutionscan be formed in any state of matter; that is they may be solid, liquid, or gas. Asolutionis prepared by dissolving asoluteinto thesolvent. Soluteis either the smaller component of a mixture or, when liquid solutions are considered, the gaseous or solid substance added to the solution. Solutionscould be composed of either complete molecules (atoms) - molecular solution, or ions - ionic solution. The latter usually is referred to aqueous solutions of salts. Fluids that mix or dissolve in each other in all proportions are callmiscible fluids, lacking that property fluids are called immiscible. So gases are always miscible miscible immiscible soluble insoluble saturated unsaturated solution dissolve precipitate (crystallize) supersaturated solution Chemistry 21A Dr. Dragan Marinkovic

  3. SOLUTIONS SOLUBILITY The maximum amount of solute that can be dissolved in a specific amount of solvent at specific temperature and pressure. NaCl(s) <==> Na+(aq) + Cl-(aq) If there is more solute dissolved than saturation allows, the solution is said to be supersaturated. supersaturated solution Chemistry 21A Dr. Dragan Marinkovic

  4. SOLUTIONS Solubility in water with temperature under 1 atm pressure, units of solubility in g/100g H2O. Substance Formula 0°C 10°C 20°C 30°C 40°C Helium He 0.6 Hydrogen chloride HCl 81 75 70 65.5 61 Fructose C6H12O6 375.0 538.0 Ammonia NH3 1176 900 702 565 428 (Unit:mL/mL) Ammonium chloride NH4Cl 29.4 33.2 37.2 41.4 45.8 Calcite CaCO3 0.0006 Magnesium carbonate MgCO3 0.039 Magnesium chloride MgCl2 52.9 53.6 54.6 Oxygen O2 .0015 0.0011 0.0009 0.0008 0.0006 Chemistry 21A Dr. Dragan Marinkovic

  5. SOLUTIONS Chemistry 21A Dr. Dragan Marinkovic

  6. SOLUTIONS Chemistry 21A Dr. Dragan Marinkovic

  7. SOLUTIONS ‘LIKE DISSOLVES LIKE” Polar solvents will dissolve polar or ionic solutes and nonpolar solvents will dissolve nonpolar or nonionic solutes. Chemistry 21A Dr. Dragan Marinkovic

  8. SOLUTIONS Chemistry 21A Dr. Dragan Marinkovic

  9. SOLUTIONS Heat of Solution The process of dissolving is a process which involves the breaking and making of bonds, and that involves energy. Dissolutionoverall can be eitherendothermic or exothermic, depending on whether more energy was used to break the bonds, or more energy was released when new bonds were formed. The breaking of bonds requires orabsorbs energy. Using energy like that is calledendothermic. If more energy is used than is released, the process is endothermic. SOLUTE + SOLVENT + HEAT SOLUTION The formation of bondsreleases energy. That is calledexothermic. If more energy is released in making bonds than is used in breaking bonds, the process is exothermic. SOLUTE + SOLVENT SOLUTION + HEAT Chemistry 21A Dr. Dragan Marinkovic

  10. SOLUTIONS CONCENTRATION Concentration -- amount of a solute present in a solution per standard amount of solvent Weight/Weight Percent (w/w%): This unit of concentration is often used for concentrated solutions, typically acids and bases. If you were to look on a bottle of a concentrated acid or base solution the concentration expressed as a weigh/weight percent. RED DYE Molarity (M): This unit of concentration Relates the moles of solute per liter of solution. w/v% milliliters of solution solute volume v/v% solution volume Chemistry 21A Dr. Dragan Marinkovic

  11. SOLUTIONS SOLUTION PREPARATION Solutionsare prepared by mixing proper amounts ofsoluteandsolventor by diluting a concentratedsolution by asolventto produce asolutionof lower concentration. a single ring graduation mark mass m density = --------- = ---- = d volume V w/v% m = d x V milliliters of solution solute volume v/v% solution volume Chemistry 21A Dr. Dragan Marinkovic

  12. SOLUTIONS SOLUTION PREPARATION Dilution is preparing a solution of lower concentration by diluting a solution of higher concentration (“stock solution”). There is an element of simplicity in calculations. The number of moles of solute in the concentrated solution is equal to the number of moles in the dilute solution. You have simply increased the amount of solvent in the solution. molescon=molesdil (Mconc) (Vconc)=(Mdil) (Vdil) This equation is true for any solution concentration based on volume. Chemistry 21A Dr. Dragan Marinkovic

  13. SOLUTIONS SOLUTION PROPERTIES Electrolyteis chemical compound that ionizes when dissolved in water to produce an electrically conductive medium. WATER SUGAR SOLUTION NaCl SOLUTION Nonelectrolyteis chemical compound that does not ionize when dissolved in water and does not produce an electrically conductive medium. NaCl(aq) Na+(aq) + Cl -(aq) Chemistry 21A Dr. Dragan Marinkovic

  14. SOLUTIONS SOLUTION PROPERTIES Vapor pressure depression Boiling point elevation The vapor pressure of a solution is lower than that of the pure solvent Freezing point depression Chemistry 21A Dr. Dragan Marinkovic

  15. SOLUTIONS SOLUTION PROPERTIES Kb = boiling constant characteristic for the solvent used Colligative property of a solutiondepends only on the ratio of the number of particles of solute and solvent in the solution, not the identity of the solute. Kf= freezingconstant characteristic for the solvent used K = constant characteristic for the solvent used ∆t = nKm ∆t = boiling or freezing point difference The factor naccounts for the number of individual particles (typically ions) formed by a compound in solution. Examples: n = 1 for sugar in water n = 2 for sodium chloride in water, due to the full dissociation of NaCl into Na+ and Cl- n = 3 for calcium chloride in water, due to dissociation of CaCl2 into Ca2+ and 2Cl- ≈ = m = M molality kg solvent For dilute Solutions. Chemistry 21A Dr. Dragan Marinkovic

  16. SOLUTIONS SOLUTION PROPERTIES ∆t = nKm Chemistry 21A Dr. Dragan Marinkovic

  17. SOLUTIONS SOLUTION PROPERTIES Osmosis In osmosis, water (solvent) flows from the lower solute concentration into the higher solute concentration. The level of the solution with the higher concentration rises. The concentrations of the two solutions become equal with time. Osmosis transfer of a liquid solvent through a semipermeable membrane that does not allow dissolved solids (solutes) to pass. Osmosis refers only to transfer of solvent; transfer of solute is called dialysis. In either case the direction of transfer is from the area of higher concentration of the material transferred to the area of lower concentration. This spontaneous migration of a material from a region of higher concentration to a region of lower concentration is called diffusion. Chemistry 21A Dr. Dragan Marinkovic

  18. SOLUTIONS SOLUTION PROPERTIES molality universal gas constant Setup for Measuring the Osmotic Pressure of a Solution temperature (K) π = nMRT Osmotic pressure is the hydrostatic pressure produced by a difference in concentration between solutions on the two sides of a surface such as a semipermeable membrane. The factor n accounts for the number of individual particles Chemistry 21A Dr. Dragan Marinkovic

  19. SOLUTIONS SOLUTION PROPERTIES Red blood cells have cell walls that are semipermeable membranes. Maintain an osmotic pressure that cannot change or damage occurs. Must maintain an equal flow of water between the red blood cell and its surrounding environment. An isotonic solution exerts the same osmotic pressure as red blood cells. is known as a “physiological solution”. of 5.0% glucose or 0.90% NaCl is used medically because each has a solute concentration equal to the osmotic pressure equal to red blood cells. Chemistry 21A Dr. Dragan Marinkovic

  20. SOLUTIONS SOLUTION PROPERTIES In dialysis, solvent and small solute particles pass through an artificial membrane. Large particles are retained inside. Waste particles such as urea from blood are removed using hemodialysis (artificial kidney). This graphic illustrates the dialysis process. First, the concentrated protein solution is placed in dialysis bag with small holes which allow water and salt to pass out of the bag while protein is retained. Next the dialysis bag is placed in a large volume of buffer and stirred for many hours (16 to 24 hours), which allows the solution inside the bag to equilibrate with the solution outside the bag with respect to salt concentration. When this process of equilibration is repeated several times (replacing the external solution with low salt solution each time), the protein solution in the bag will reach a low salt concentration: Chemistry 21A Dr. Dragan Marinkovic

  21. SOLUTIONS SOLUTION PROPERTIES In hemodialysis, the patient's blood is pumped through the blood compartment of a dialyzer, exposing it to a semipermeable membrane. The cleansed blood is then returned via the circuit back to the body. Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. Chemistry 21A Dr. Dragan Marinkovic

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