1 / 46

Solutions

Solutions. From Chapters 12 and 13. Reading. Chapter 12 Section 1 (pp. 363-366) Section 4 (pp. 384-385) Chapter 13 all (pp.395-418). Solutions. homogenous mixture 2 parts 1. solute - dissolved 2. solvent - does dissolving (greatest amount). Solution examples. The Universal Solvent.

kdutton
Download Presentation

Solutions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solutions From Chapters 12 and 13

  2. Reading • Chapter 12 • Section 1 (pp. 363-366) • Section 4 (pp. 384-385) • Chapter 13 • all (pp.395-418)

  3. Solutions • homogenous mixture • 2 parts 1. solute - dissolved 2. solvent - does dissolving (greatest amount)

  4. Solution examples

  5. The Universal Solvent Water H2O • a part of almost every liquid on earth • shape – bent • polar • high surface tension • capillary action • hydrogen bonding

  6. Distinguish between… soluble • if it will dissolve miscible • liquids that will dissolve in one another insoluble • if it will NOTdissolve immiscible • liquids that will NOTdissolve in one another

  7. Types of solutions

  8. 1. solid solutions • alloys – two or more solids evenly mixed • steel, brass • amalgam – an alloy containing mercury • uses in dentistry, gold extraction, industry

  9. 2. gas solutions • gas dissolved in gas • i.e. air • oxygen and other gases dissolved in nitrogen

  10. 3. liquid solutions • aqueous solutions • solvent is water • tincture solutions • solvent is alcohol • tincture of iodine miscible/immiscible

  11. “like dissolves like” • solvation – interaction of solute and solvent • polar solvents dissolve polar and ionic substances • non-polar solvents dissolve non-polar substances

  12. hydrate • when a compound contains water i.e. • hydrated copper sulfate • CuSO4 ∙ 5H2O • copper sulfate pentahydrate

  13. Suspensions • particles are larger than in solutions • particles evenly distributed by a mechanical means (i.e. shaking the contents) • BUT the components will settle out.

  14. Suspension Examples • mud, muddy water • paint • flour suspended in water • dust in air • algae in water

  15. Colloids • particles intermediate in size between solutions and suspensions • microscopically evenly distributed without settling out • ‘colloidal particles’ or colloids • ‘colloidal dispersion’ • A colloidal dispersion consists of colloids in a dispersing medium. • Liquids, solids, and gases all may be mixed to form colloidal dispersions.

  16. Colloid Examples • Aerosols: solid or liquid particles in a gas. • Examples: Smoke is a solid in a gas. Fog is a liquid in a gas. • Sols: solid particles in a liquid • Example: Milk of Magnesia is a sol with solid magnesium hydroxide in water. • Emulsions: liquid particles in liquid. • Example: Mayonnaise is oil in water. • Gels: liquids in solid. • Examples: gelatin is protein in water. Quicksand is sand in water.

  17. How to tell apart? • suspension particles will separate • colloids display Tyndall Effect • Tyndall effect - Light passing through a colloidal dispersion will be reflected by the larger particles and the light beam will be visible • solutions will not separate or scatter light

  18. Electrolytes • if something conducts electricity in solution – electrolyte • if not – non-electrolyte • if it conducts a little electricity – weak electrolyte

  19. Factors Affecting Rate of Dissolving • nature of the solute and solvent

  20. Factors Affecting Rate of Dissolving • temperature • higher temperature, more solute can go into solution • gases are opposite

  21. Factors Affecting Rate of Dissolving • pressure • increased pressure increases gas solubility • doesn’t affect liquids or solids

  22. Factors Affecting Rate of Dissolving • particle size • smaller particles dissolve faster • ‘increase surface area’

  23. Factors Affecting Rate of Dissolving • agitation • stirring increases rate of dissolution

  24. Henry’s Law • at a given temperature, the solubility of a gas in a liquid (S) is directly proportional to the pressure of a gas above the liquid (P) S1 = S2 P1 P2

  25. Solution concentration • solubility • the amount of solute dissolved in a given solvent at a specific temperature • i.e. solubility of sugar is 204 g per 100. g of water at 20 C • concentration • amount of solute in a given amount of solvent or solution • measured in molarity (mol/L) or molality (mol/kg)

  26. Saturation • saturated • maximum solubility • solution holds as much solution as possibleunder given conditions (T&P) • unsaturated • less than maximum • supersaturated • greater than maximum • grows crystals • i.e. rock candy

  27. Relative concentration • concentrated – large amount of solute in small amount of solvent • dilute – small amount of solute in large amount of solvent • relative amounts, depends on what you compare it to

  28. Molarity molarity (M) M = moles of solute liters of solution unit - mol/L M1V1 = M2V2

  29. Examples • A saline solution contains 0.90g NaCl per 100 mL of solution. What is its molarity? • A salt solution has a volume of 250 mL and contains 0.70 mol of NaCl, what is the molarity? • How many moles of solute are present in 1.5 L of 0.2 M Na2SO4?

  30. Examples • What volume of MgSO4 is needed to prepare 100 mL of 0.4M solution from a 2.0 M solution? • You need 250 mL of 0.20 M NaCl, but you only have a 1.0 M solution of sodium chloride, what do you do?

  31. % solution • % by volume • volume solute/volume solution x 100 • % by mass/volume • mass of solute/volume of solution x 100 • g and mL • ppm – number of grams per million grams

  32. Examples • What is the percent by volume of ethanol (C2H6O) in the final solution when 75 mL of ethanol is diluted to a volume of 250 mL with water? • How many grams of glucose would you need to prepare 2.0L of 2.0% sucrose (m/v) solution?

  33. Mixed Review • A solution contains 2.7 g of CuSO4 in 75 mL of solution. What is the percent (m/v) of the solution? • How many moles of solute are in 250 mL of 2.0 M CaCl2? How many grams of CaCl2 is this? • How many grams of magnesium sulfate are required to make 250 mL of a 1.6% MgSO4 (m/v) solution

  34. Mixed Review • If 10 mL of acetic acid is diluted with 190 mL of water, what is the percent by volume of the acetic acid? • An aqueous solution has a volume of 2.0 L and contains 36.0 g of glucose. If the molar mass of glucose is 180 g, what is the molarity of the solution?

  35. Class work • In grey books • pg 390 • #26, 27, 28 (a-c), 30(a-b), 31 (a-b), 33 your books - pg 942 #367-373 Homework

  36. Molality molality (m) m = moles solute kg solvent unit: mol/kg

  37. Examples • How many grams of potassium iodide must be dissolved in 500. g of water to produce 0.060 molal KI solution? • Calculate the molality of a solution prepared by dissolving 10.0 g of NaCl in 600.g of water.

  38. mole fraction number of moles of one component divided by total number of moles of solution • represented by Xx Xsolute = moles of solute moles of solution Xsolvent = moles of solvent moles of solution Xsolute +Xsolvent 1

  39. Examples • Compute the mole fraction of each component in a solution of 1.25 mol ethylene glycol (EG) and 4.00 mol water. • What is the mole fraction of each component in a solution made by mixing 300. g of ethanol and 500. g of water? • A solution is labeled 0.150 molalNaCl.What are the mole fractions of the solute and the solvent in this solution?

  40. Class work • In your blue books • pg 421 • 15b, 16, 17, 19c, 23, 24, 26, 28, 29, 32 • Homework: pg 941 • 338-340, 350, 352, 365

  41. Colligative Properties *note: colligative properties will be bonus questions on the test. • property that depends on concentration • 4 types • vapor pressure reduction • boiling point elevation • freezing point depression • osmotic pressure

  42. vapor pressure reduction • vapor pressure over a solvent is reduced when a solute is dissolved in the solvent

  43. boiling point elevation • amount by which the boiling point is raised when a solute is in solution • ∆Tb = Kbm(i) • Kb – molal boiling point constant • m – molality • (i)Van’t Hoff factor

  44. freezing point depression • a dissolved solute lowers the freezing point • ∆Tf = Kfm(i) • Kf – freezing point depression constant • m – molality • (i)Van’t Hoff factor

  45. osmotic pressure • pressure required to prevent osmosis • osmosis – net flow of solvent molecules from less concentrated solution to more concentrated solution

More Related