March 30, Chapter 22 Notes.notebook. Section 1: How Solutions form

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1 Thursday, March 23 rd 1) No QOTD 2) Finish presentations 3) Intro to Chapter 22: Solutions Section 1: How Solutions form A. Solution a mixture that appears the same throughout and is mixed at the molecular level. 1. Solute substance being dissolved 2. SolVent substance doing the dissolving. 3. Solutions can be liquids, gases, or solids. 4. Alloys are solid solutions. Mar 14 12:51 PM Mar 14 12:55 PM Gas in Liquid Similar to Solid in Water Ex pop Solid in a Solid Melt then mix Ex alloy B. How dissolving happens: Solid in Water 1. Water molecules are polar they have a positive area with a negative area. Mar 14 1:06 PM Mar 14 12:59 PM Water molecules cluster around solid molecules: negative ends attracted to the positive ends of the solids. water molecules pull the solid particles into solution. The moving water molecules and solid molecules spread out and mix evenly to form a solution Ex. sugar and water. To mix solids to make an alloy solution, you must melt the solids. To Speed Up: 1. stir 2. grind or get more surface area 3. heat Mar 23 8:28 AM Mar 23 8:29 AM 1

2 C. Rate of Dissolving depends on: 1. Stirring speeds up dissolving by bringing more fresh solvent into contact with more solute. 2. Crystal Size > dissolving occurs at the surface of a solid > Breaking a solid into pieces or powder increases its surface area, which speeds up dissolving. 3. Temperature increasing the temp. of a solvent speeds up the movement of its particles. 4. To make a gas dissolve more quickly in a liquid: 1. cool the liquid 2. increase the pressure of the gas 3. Do not agitate. Mar 14 1:09 PM Mar 14 1:12 PM Tuesday, March 28th 1) Answer the QOTD: "What happens to the solubility of gases and solids when you increase the temperature?" 2) Take out Lab from Friday (Varying Speed of Chemical rxns)! Mar 18 3:02 PM Mar 28 8:36 AM SR p Liquid/liquid, solid/ liquid, gas/liquid, gas/ gas, solid/solid 2. Increasing temperature causes particles to move faster which causes solutes to dissolve faster. 3. Metals are melted, mixed evenly, then cooled to a solid. 4. Yes, one metal acts as the solute while the other metals acts as a solvent. 5. 2(2cmx1cm) + 2(2cmx0.5cm) + 2(1cmx0.5cm) = 7 cm 2 6. new l= 2.2 cm; therefore new SA= 7.6 cm (7.6cm 7cm) 7cm *100 = 8.5% increase Section 2: Solubility and Concentration A. Solubility "ability to dissolve" (at a given temperature!) 1. Depends on the nature of the substances 2. Solubility of two substances can be compared by measuring. Ex. Li 2 CO 3 (Lithium Carbonate) 1.3 g/ 100 ml of H 2 O If you raise the temperature, you can dissolve more Mar 21 11:23 AM Mar 14 1:15 PM 2

3 B. Concentration "how much solute compared to solvent" 1. A concentrated solution has a large amount of solute in the solvent. Ex. frozen OJ 2. A dilute solution has a small amount of solute in the solvent. OJ (little solute, much solvent) 3. Concentrations can be expressed as percent by volume of the solute. (100% orange juice vs. capri sun) Mar 14 1:19 PM Mar 21 8:44 AM C. Types of solutions: 1. Saturated solution contains all the solute it can hold at a given temperature. a. As the temperature of a liquid solvent increases, the amount of solid solute that can dissolve in it increases. b. Solubility curve line on a graph used to figure how much solute can dissolve at any temperature on the graph. Solubility Curve > shows the dependence of solubility on temperature Mar 14 1:22 PM Mar 21 8:49 AM 2. Unsaturated solution able to dissolve more solute at a given temperature. 3. Super saturated solution contains more solute than a saturated one at the same temperature (must be done in lab not commonly found in nature) more solute dissolves no more solute dissolves becomes unstable, crystals form a. made by raising the temp. of a saturated solution, adding more solute, and lowering the temperature back without disturbing the solution. b. Sodium acetate will crystallize if disturbed. c. As it crystallizes, it gives off energy that produces heat. Mar 14 1:25 PM Mar 21 8:25 AM 3

4 Solubility of Gases 1. Pressure effects to dissolve more gas in a liquid, increase pressure. Ex. soft drinks bottled under increased pressure.. CO 2 bubbles out when opened. 2. Temperature effects cooling the liquid will increase the amount of gas that dissolves in a liquid (opposite of what you do to a solid to dissolve it.) Ex. carbon dioxide will bubble out as a soft drink gets warmer. Mar 14 1:29 PM Mar 28 8:50 AM Tuesday, March 29th 2) Answer the QOTD: "What do we call any solution that can dissolve more solute at a given temperature." 3) Take out notetaking guide for Ch Section 3: Particles in Solution A. Ions particles with a charge 1. Electrolyte compounds that form charged particles (ions) and conduct electricity in water. 2. Nonelectrolyte substances that do not ionize in water and cannot conduct electricity. Mar 29 8:49 AM Mar 16 1:22 PM 2 WAYS TO DISSOLVE PARTICLES IN SOLVENT B. How ions form 1. Ionization molecules break apart in water, causing atoms to become ions by taking on a charge. Ex. HCl in H 2 O... water pulls polar molecules apart and forms ions H 3 O + (hydronium ion) and Cl (chloride ions) 2. Dissociation an ionic solid separates into its positive and negative ions. Ex. Separates into ions NaCl in H 2 O polar ends of water attract oppositely charged ionic solid ends and separate them Mar 16 1:28 PM Mar 21 1:05 PM 4

5 C. Effects of Solute particles 1. All solute particles polar, nonpolar, electrolyte, and nonelectrolyte affect the physical properties of the solvent. 2. Adding a solute to a solvent lowers the freezing point because the added solute particles interfere with the formation of the orderly freezing pattern. 3. Adding a solute raises the boiling point because fewer solvent molecules can reach the surface and evaporate. Why do we need Antifreeze? In the summer, increases bp so radiator will not over heat. In the winter, decreases fp so radiator will not freeze. Certian animals that live in extremely cold climates have thier own kind of antifreeze (ex. glycoprotein) Mar 21 8:15 AM Mar 21 1:26 PM Thursday, March 30th 1. Answer the QOTD: "How many grams of KCl are needed to make a saturated solution at 30 o C?" Solubility of KNO 3 Lab: 2. Take out solubility of KNO 3 lab Mar 30 8:41 AM Mar 29 9:38 AM Friday, March 31 st 1) Answer the QOTD: "What are the three ways to increase the rate of dissolving a solid in a liquid?" 2) Take out BP of solution lab Mar 30 4:52 PM Mar 30 9:02 AM 5

6 SR #2 p no you can determine this experimentally g 3. solute z 4. unsaturated 5. when capped, carbon dioxide stays in solution, which keeps the soda "fizzy" SR #3 p dissociation 2. electrolytes; ions and nonelectrolytes; molecules 3. the particles in the crystal are separated and drawn into solution by water molecules. 4. as the concentration rises, the boiling point increases until saturation is reached. 5. the ions from the salt have disrupted the crystal lattice formed by water when it freezes. The temperature will have to be lower for the molecules of water to freeze. Mar 30 8:29 AM Mar 30 8:30 AM Section 4: Dissolving without Water A. Nonpolar materials have no positive or negative areas. 1. They are not attracted to the polar water molecules, so they do not dissolve easily in water. 2. Example: oils contain hydrocarbons. a. Large molecules of carbon and hydrogen atoms b. These atoms share electrons in an equal manner, so there is not positive or negative charge. Nonpolar solutes oil (hydrocarbon) and vinegar (acetic acid in water) Mar 21 1:09 PM Mar 21 1:11 PM B. Useful nonpolar molecules 1. * Nonpolar solvents dissolve nonpolar solutes * Polar solvents dissolve polar solutes "Like dissolves like" 2. Many nonpolar solvents are toxic dangerous to touch or inhale. **Water is "HARD" when there are lots of dissolved substances in it. Water is "SOFT" when there are not a lot of dissolved substances. Mar 21 1:12 PM Mar 29 8:41 AM 6

7 3. Soap used for washing because it has polar and non polar properties C. Polarity and vitamins 1. B vitamins and vitamin C are polardissolve in the water in your body cells. 2. Vitamin A is nonpolar dissolves in the fat (nonpolar) of some body cells. Mar 29 8:00 AM Mar 21 1:14 PM Monday, April 3 rd 2) Answer the QOTD "Is iodine (I 2 ) polar or nonpolar? Which substance would dissolve Iodine?" a) water b) ethanol c) polar solvent d)vinegar 3) Take out mastery and a pen to correct Friday, April 1, ) Answer the QOTD: "What happens to a saturated solution when it cools down?" 3) Take out Boiling Point of Solution Lab Mar 30 8:55 AM Apr 1 8:49 AM SR p.685 Tuesday, April 4th 2) Answer the QOTD "How does the solubility of gases depend on temperature and pressure?" 3) Take out Ch. Review Questions Mar 29 10:21 AM Apr 1 9:29 AM 7

8 Wednesday, April 5th 2) Answer the QOTD: "How many grams of salt are needed to make a 30% saltwater solution?" Apr 5 9:00 AM Mar 30 4:57 PM 8