Chemistry Matter and Change - PowerPoint
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Mixtures and Solutions Section 14.1 Types of Mixtures Section 14.2 Solution Concentration Section 14.3 Factors Affecting Solvation Section 14.4 Colligative Properties of Solutions Click a hyperlink or folder tab to view the corresponding slides. Exit Section 14.1 Types of Mixtures • Compare the properties solute: a substance of suspensions, colloids, dissolved in a solution and solutions. • Identify types of colloids suspension and types of solutions. colloid • Describe the electrostatic Brownian motion forces in colloids. Tyndall effect soluble Mixtures can be either miscible heterogeneous or insoluble homogeneous. immiscible Heterogeneous Mixtures • A heterogeneous mixture is a mixture that does not have a uniform composition and in which the individual substances remain distinct. • Suspensions are mixtures containing particles that settle out if left undisturbed. (Like dirty water) Heterogeneous Mixtures (cont.) • Colloids are heterogeneous mixtures of intermediate sized particles (between 1 nm and 1000 nm) and do not settle out. • Colloids are categorized according to the phases of their particles. Heterogeneous Mixtures (cont.) Heterogeneous Mixtures (cont.) • The Tyndall effect is when dispersed colloid particles scatter light. • Both suspensions and solutions display this. • Tyndall effect Homogeneous Mixtures • Solutions are homogeneous mixtures that contain two or more substances called the solute and solvent. • Most solutions are liquids, but gaseous and solid solutions exist. Homogeneous Mixtures (cont.) Homogeneous Mixtures (cont.) • A substance that dissolves in a solvent is soluble. • Two liquids that are soluble in each other in any proportion are miscible. • A substance that does not dissolve in a solvent is insoluble. • Two liquids that can be mixed but separate shortly after are immiscible. Section 14.1 Assessment Miscible substances are: A. two liquids that are not soluble in each other B. solids that dissolve in liquids C. solids that do not dissolve in A. A liquids B. B D. two liquids that are soluble in C. C each other 0% 0% 0% 0% D. D A B C D Section 14.1 Assessment The jerky, random movement of particles in a liquid colloid is known as ____. A. Brownian motion B. Tyndall effect C. Charles’s Law A. A D. kinetic energy B. B C. C 0% 0% 0% 0% D. D A B C D • Self check quizzes Section 14.2 Solution Concentration • Describe concentration solvent: the substance using different units. that dissolves a solute to form a solution • Determine the concentrations of solutions. concentration • Calculate the molarity of molarity a solution. molality mole fraction Concentration can be expressed in terms of percent or in terms of moles. Expressing Concentration • The concentration of a solution is a measure of how much solute is dissolved in a specific amount of solvent or solution. • Concentration can be described as concentrated or dilute. • Many ways to express this • % by mass or volume • like D5W which is a 5% sugar solution or normal saline which is 0.9% sodium chloride (table salt) in IV solutions • A volume example is 70% isopropyl (rubbing) alcohol Expressing Concentration (cont.) Expressing Concentration (cont.) • The equation is • Mass (or volume) of solute ÷ mass (or volume) of solution x 100 • How would you make up a normal saline solution? • .9 g of NaCl up to 100 mL of water • Do problems 9-11 page 481 • Check your answers on 1000 10)54.3 g • Do problems 13,14 page 482 14) 2.1% Expressing Concentration (cont.) • Molarity is the number of moles of solute dissolved per liter of solution. • Molarity ( M)is a more precise way to do concentration as it goes by particles not mass • Moles of solute ÷ liters (dm3) of solution • M = mole/liter • What is the molarity of a normal saline solution 0.9 g in 100 mL of water solution? • 0.9 / 58.5 g/mol = 0.0154 100ml /1000= .1 • 0.154 M • What is the molarity of a D5W solution 5 g of dextrose (mm 180) in 100 mL of water ? • • 0.278 M • Do 16-19 page 483 • Answers on page 1000 16) 0.148 M 18) 0.128 M • How do you make up 500 mL of a 0.25 molar NaCl solution? • 0.25 mol/L x 0.5 L = 0.125 mol • 0.125 mol x mm(58.5 g/mol) = 7.31 g of NaCl • Put 7.31 g in a volumetric flask and dilute to 500 mL • Do problems 20-22 page 484 • Check you answers on page 1000 20) 11g 22) 30. g • How many grams of NaCl are dissolved in 500.0 mL of a 0.05M solution of NaCl? A)0.05 g B)0.29 g C)1.46 g D)2.92 g • Prepare 500 mL of a 0.1 M HCl solution using a 12 M stock solution • M1V1 = M2V2 • 12 M x V1 = 0.1 M x 0.500 L • V1 = (0.1M x 0.500 L) ÷ 12 M • Use 0.00417 L or 4.17 mL and dilute to 500 mL • Do 24 and 25 page 486 • Answers on page 1000 24) 125 mL • To avoid the change in volume due to temperature a unit using mass is used • m = mol of solute / kg of solvent • 9.00 grams of NaCl is added to (not diluted to)500 g of water. What is its molality • 9/58.5 mol ÷0.500 kg = 0.171 m Expressing Concentration (cont.) • Molality is the ratio of moles of solute dissolved in 1 kg of solvent. • Do 27 and 28 page 487 28) 171g answers on page 1000 Expressing Concentration (cont.) • Mole fraction is the ratio of the number of moles of solute in solution to the total number of moles of solute and solvent. where XA and XB represent mole fractions of each substance We will not test on this Section 14.2 Assessment Which is NOT a quantitative measure of concentration? A. molarity B. molality C. percent by mass A. A D. dilute B. B C. C 0% 0% 0% 0% D. D A B C D Section 14.2 Assessment The number of moles of solute divided by liters of solvution is called ____. A. molarity B. molality C. percent by volume A. A D. percent by mass B. B C. C 0% 0% 0% 0% D. D A B C D • Self check quizzes Section 14.3 Factors Affecting Solvation • Describe how exothermic: a chemical intermolecular forces reaction in which more affect solvation. energy is released than is required to break • Define solubility. bonds in the initial reactants • Understand what factors affect solubility. Section 14.3 Factors Affecting Solvation (cont.) solvation heat of solution unsaturated solution saturated solution supersaturated solution Henry’s law Factors such as temperature, pressure, and polarity affect the formation of solutions. The Solvation Process • Solvation is the process of surrounding solute particles with solvent particles to form a solution. • Solvation in water is called hydration. • The attraction between dipoles of a water molecule and the ions of a crystal are greater than the attraction among ions of a crystal. The Solvation Process (cont.) The Solvation Process (cont.) • Sucrose molecules have several O–H bonds, which become sites for hydrogen bonding with water molecules. • Oil does not form a solution with water because there is little attraction between polar water molecules and nonpolar oil molecules. The Solvation Process (cont.) • During solvation, the solute must separate into particles and move apart, which requires energy. • The overall energy change that occurs during solution formation is called the heat of solution. Factors That Affect Solvation • Stirring or shaking moves dissolved particles away from the contact surfaces more quickly and allows new collisions to occur. • Breaking the solute into small pieces increases surface area and allows more collisions to occur. • As temperature increases, rate of solvation increases. Solubility • Solubility depends on the nature of the solute and solvent. • Unsaturated solutions are solutions that contain less dissolved solute for a given temperature and pressure than a saturated solution. Solubility (cont.) • Saturated solutions contain the maximum amount of dissolved solute for a given amount of solute at a specific temperature and pressure. • Solubility is affected by increasing the temperature of the solvent because the kinetic energy of the particles increases. At what temperature is KCl saturated with 46 g? What is the general trend for solubilities of solids in water? Solubility (cont.) • A supersaturated solution contains more dissolved solute than a saturated solution at the same temperature. • To form a supersaturated solution, a saturated solution is formed at high temperature and then slowly cooled. • Supersaturated solutions are unstable. Solubility (cont.) Solubility (cont.) • Gases are less soluble in liquid solvents at high temperatures. • Solubility of gases increases as its external pressure is increased. • Henry’s law (not tested on this) states that at a given temperature, the solubility (S) of a gas in liquid is directly proportional to the pressure (P). • Why do pop bottles foam over when they are warm and you shake them up? Section 14.3 Assessment For a given amount, which type of solution contains the LEAST amount of solute? A. solvated B. saturated A. A C. supersaturated B. B D. unsaturated C. C 0% 0% 0% 0% D. D A B C D Section 14.3 Assessment At a given temperature, the solubility of a gas is directly proportional to what? A. volume B. mass C. molarity A. A D. pressure B. B C. C 0% 0% 0% 0% D. D A B C D • Section quiz Section 14.4 Colligative Properties of Solutions • Describe colligative ion: an atom that is properties. electrically charged • Identify four colligative properties of solutions. • Determine the boiling point elevation and freezing point depression of a solution. Section 14.4 Colligative Properties of Solutions (cont.) colligative property vapor pressure lowering boiling point elevation freezing point depression osmosis osmotic pressure Colligative properties depend on the number of solute particles in a solution. Electrolytes and Colligative Properties • Colligative properties are physical properties of solutions that are affected by the number of particles but not by the identity of dissolved solute particles. • Ionic compounds are electrolytes because they dissociate in water to form a solution that conducts electricity. • Some molecular compounds are also electrolytes. Electrolytes and Colligative Properties (cont.) • Electrolytes that produce many ions in solution are strong electrolytes. Vapor Pressure Lowering • Adding a nonvolatile solute to a solvent lowers the solvent’s vapor pressure. • When a solute is present, a mixture of solvent and solute occupies the surface area, and fewer particles enter the gaseous state. • The greater the number of solute particles, the lower the vapor pressure. Vapor Pressure Lowering (cont.) • Vapor pressure lowering is due to the number of solute particles in solution and is a colligative property of solutions. Boiling Point Elevation • When a nonvolatile solute lowers the vapor pressure of a solvent, the boiling point is also affected. (elevated) • More heat is needed to supply additional kinetic energy to raise the vapor pressure to atmospheric pressure. Freezing Point Depression • At a solvent's freezing point temperature, particles no longer have sufficient kinetic energy to overcome interparticle attractive forces. • The freezing point of a solution is always lower than that of the pure solvent. Freezing Point Depression (cont.) • Solute particles interfere with the attractive forces among solvent particles. • A solution's freezing point depression is the difference in temperature between its freezing point and the freezing point of the pure solvent. Osmotic Pressure • Osmosis is the diffusion of a solvent through a semipermeable membrane. Osmotic Pressure (cont.) • Osmotic pressure is the amount of additional pressure caused by water molecules that moved that moved into the concentrated solution. Section 14.4 Assessment Nonvolatile solutes ____ the vapor pressure of a solution. A. increase B. decrease C. do not change A. A D. unpredictably change B. B C. C 0% 0% 0% 0% D. D A B C D Section 14.4 Assessment Colligative properties of a solution depend on: A. the type of solute B. the type of solvent C. the vapor pressure of the A. A solvent B. B D. the number of particles of C. C solute 0% 0% 0% 0% D. D A B C D • Section 4 quiz Chemistry Online Study Guide Chapter Assessment Standardized Test Practice Image Bank Concepts in Motion Chemistry Online Study Guide Chapter Assessment Standardized Test Practice Image Bank Concepts in Motion Section 14.1 Types of Mixtures Key Concepts • The individual substances in a heterogeneous mixture remain distinct. • Two types of heterogeneous mixtures are suspensions and colloids. • Brownian motion is the erratic movement of colloid particles. • Colloids exhibit the Tyndall effect. • A solution can exist as a gas, a liquid, or a solid, depending on the solvent. • Solutes in a solution can be gases, liquids, or solids. Section 14.2 Solution Concentration Key Concepts • Concentrations can be measured qualitatively and quantitatively. • Molarity is the number of moles of solute dissolved per liter of solution. • Molality is the ratio of the number of moles of solute dissolved in 1 kg of solvent. Section 14.2 Solution Concentration (cont.) Key Concepts • The number of moles of solute does not change during a dilution. M1V1 = M2V2 Section 14.3 Factors Affecting Solvation Key Concepts • The process of solvation involves solute particles surrounded by solvent particles. • Solutions can be unsaturated, saturated, or supersaturated. • Henry’s law states that at a given temperature, the solubility (S) of a gas in a liquid is directly proportional to the pressure (P) of the gas above the liquid. Section 14.4 Colligative Properties of Solutions Key Concepts • Nonvolatile solutes lower the vapor pressure of a solution. • Boiling point elevation is directly related to the solution’s molality. ∆Tb = Kbm • A solution’s freezing point depression is always lower than that of the pure solvent. ∆Tf = Kfm • Osmotic pressure depends on the number of solute particles in a given volume. When dispersed solids in a colloid scatter light, it is known as ____. A. Tyndall effect B. Brownian motion C. Henry’s law A. A D. Charles’s law B. B C. C 0% 0% 0% 0% D. D A B C D Molality is: A. the number of moles of solute divided by liters of solution B. the volume of solute divided by liters of solution A. A C. the volume of solute divided by the volume of solution B. B C. C D. the number of moles of solute 0% 0% 0% 0% divided by kg of solvent D. D A B C D Which is NOT a type of solution? A. saturated B. unsaturated C. polyunsaturated A. A D. supersaturated B. B C. C 0% 0% 0% 0% D. D A B C D The addition of a nonvolatile solute to a solution: A. increases the freezing point of the solution B. increases the vapor pressure of the solution A. A C. lowers the boiling point of B. B the solution C. C 0% 0% 0% 0% D. decreases vapor pressure of D. D A B C D the solution Solutes in a solution can be: A. liquids only B. liquids and solids only C. gases and solids only A. A D. gases, liquids, or solids B. B C. C 0% 0% 0% 0% D. D A B C D Which is NOT an intensive physical property? A. volume B. hardness C. density A. A D. mass B. B C. C 0% 0% 0% 0% D. D A B C D Cl2(g) + 2NO(g) → 2NOCl is what type of reaction? A. dehydration B. synthesis C. fusion A. A D. replacement B. B C. C 0% 0% 0% 0% D. D A B C D If 8 mol of H2 is used, how many moles of Fe will be produced? Fe3O4(s) + 4H2 →3Fe(s) + 4H2O(l) A. 2 B. 3 A. A C. 4 B. B D. 6 C. C 0% 0% 0% 0% D. D A B C D Which is NOT a colligative property? A. heat of solution B. boiling point elevation C. vapor pressure lowering A. A D. freezing point depression B. B C. C 0% 0% 0% 0% D. D A B C D Nonvolatile solutes _____ the boiling point of a solution. A. increase B. decrease C. do not change A. A D. unpredictably change B. B C. C 0% 0% 0% 0% D. D A B C D Click on an image to enlarge. Table 14.2 Types and Examples of Solutions Figure 14.10 Dissolution of Compounds Figure 14.19 Strong, Weak, and Non-Electrolytes Figure 14.23 Osmosis Click any of the background top tabs to display the respective folder. Within the Chapter Outline, clicking a section tab on the right side of the screen will bring you to the first slide in each respective section. Simple navigation buttons will allow you to progress to the next slide or the previous slide. The Chapter Resources Menu will allow you to access chapter specific resources from the Chapter Menu or any Chapter Outline slide. From within any feature, click the Resources tab to return to this slide. 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