Do Now Create a list (at least 4 items) of 5 common solutions, give a reason for why you think each one is a solution.

Ch 12.1 Types of Mixtures

Essential Question What is the difference between a heterogeneous mixture and a homogeneous mixture and how do they compare to solutions, suspensions, and colloids?

Heterogeneous vs. Homogeneous Mixtures There are two basic types of mixtures:- Heterogeneous Mixture: mixture does not have a uniform composition. Ex: Milk and soil Homogeneous Mixture: entire mixture has the same or uniform composition. Ex: Salt water Homogeneous mixtures are also called solutions

Solutions Solution is a homogeneous mixture of two or more substances in a single phase Soluble: capable of being dissolved. Ex. Sugar is soluble in water. Sugar and water create a solution,

Components of a Solution Solvent: the substance that does the dissolving. Usually the greater quantity in the solution Solute: the substance that is being dissolved. Usually the lesser quantity of the solution.

Solute and Solvent Can you separate a solution? How?

Solutions may exist as gases, liquids, or solids, and may also be combinations. Solute StateSolvent StateExample Gas Liquid Solid Liquid Solid Oxygen in Nitrogen CO2 in water/syrup Alcohol in water Mercury in Silver and Tin Sugar/salt in water Copper in Nickel alloy

Suspensions Suspension: When the particles in a solvent are so large that they settle out unless the mixture is constantly agitated. Ex: Muddy water The particles in a suspension can be separated by passing the mixture through a filter.

Colloids Particles that are intermediate in size between those in solutions and suspensions form mixtures called colloids. These are also known as emulsions and foams and cannot be separated using a filter. Ex. Mayonnaise and Milk

Colloids Class of ColloidPhasesExample SolSolid in liquidPaints, mud GelSolid in liquidGelatin Liquid EmulsionLiquid in liquidMilk, Mayonnaise FoamGas in liquidShaving cream, whipped cream Solid aerosolSolid in gasViruses, particulate matter Liquid aerosolLiquid in gasFog, mist, Solid emulsionLiquid in solidCheese, butter

Tyndall Effect Tyndall Effect: when light is scattered by the large particles in a colloid. Can be used to determine a solution or colloid Light is scattered because of the rapid movement of the molecules of the solute Brownian motion is the rapid movement of molecules

Solutes: Electrolytes vs. Nonelectrolytes Electrolyte: a substance that dissolves in water to give a solution that conducts an electric current. Nonelectrolyte: a substance that dissolves in water to give a solution that doesn’t conduct an electric current.

Practice Ch 12.1 pg 406 #1, 2, 6 and pg 426 #3-5

Ch 12.2 The Solution Process

Do Now What do you think are some factors that affect the rate at which a solute dissolves in a solvent?

Factors Affecting Dissolution Rate Three factors that affect dissolving rate: Stirring (agitation) Temperature Increasing the surface area of the dissolving particles.

Stirring’s Affect on Dissolution Stirring or shaking a solution helps to disperse solute particles and bring fresh solvent in contact with the solute surface.

Increasing Surface Area Dissolution begins at the surface of the solute, Crushing will increase the surface area of a solute The solvent can now come in contact with many surface at once, increasing dissolution

Heating or Increasing Solvent Temperature As temperature increases, molecules move faster As molecules move faster, more collisions occur between the solvent and solute molecules Solute is separated at a higher rate.

Solubility Every solution has a dissolution limit at a given temperature Different for every solute- solvent combination Solution equilibrium is the physical state in which dissolution and crystallization happen at equal rates

Solubility Solubility tells us how much solute can dissolve in a certain amount of solvent at a particular temperature and pressure to make a saturated solution. Expressed in grams of solute per 100 grams of solvent

Saturated Vs Unsaturated Saturated Solution: the solution cannot hold any more solute. Unsaturated Solution: the solution could still dissolve more solute. Supersaturated Solution: the solution is holding more than it should at the given temperature, and if you disturbed with the solution by shaking it or adding even one more crystal of solute, the whole thing would crystallize rapidly.

Solubility Values Solubility Values: amount of substance required to form a saturated solution with a specific amount of solvent at a specified temperature. Solubility of sugar is 204 grams per 100 grams of water at 20°C.

Solute-Solvent Interactions “ Like dissolves Like” Polar will dissolve other polar molecules and Nonpolar dissolves other nonpolar. Water is a universal solvent Hydration: when water is used to dissolve an ionic solution.

Hydrates Hydrates are formed when ionic substances form crystals that incorporate the dissolving water molecule. Hydrates are represented by formulas stating the amount of water incorporated with the crystal. eg. CuSO 4. 5H 2 O

Liquid Solutes and Solvents Miscible: two liquids that can dissolve in each other. Immiscible: the liquids don’t mix. Ex. Oil and vinegar

Factors Affecting Solubility Temperature affects the solubility of: Solid Solutes Liquid Solutes Gaseous Solutes

Temperature Gas dissolved in a Liquid: as the temperature increases, the solubility decreases. Example: Warm soda loses its carbonation. Solid dissolved in a Liquid: as the temperature increases, the solubility increases. Example: Sugar in hot tea versus iced tea. Pressure affects the solubility of: Gaseous Solutes

Pressure Gas dissolved in Liquid: As pressure increases, solubility increases. Example: Soda is carbonated under high pressure. Solid dissolved in Liquid: As pressure increases, solubility does not change! Since you cannot compress solids and liquids, pressure has no effect on solubility.

Henry’s Law Applies to gas-liquid solutions at constant temperatures. The solubility of a gas in a liquid is directly proportional to the partial pressure of that gas on the surface of the liquid S 1 = S 2 P 1 P 2 The escape of gas from a liquid is called effervescence.

Calculating Solubility of a Gas If the solubility of a gas in water is 0.77 g/L at 3.5 atm of pressure, what is its solubility (g/L) at 1.0 atm of pressure and a constant temperature? P 1 = 3.5 atm S 1 = 0.77 g/L P 2 = 1.0 atm S 2 = ? g/L 0.77 g/L = S atm 1.0 atm S 2 = 0.22 g/L

Enthalpies of Solution Solvated: when a solute particle is surrounded by solvent molecules. The formation of a solution is accompanied by an energy change, it can be released or absorbed. Enthalpy of solution: the net amount of energy absorbed as heat by the solution when a specific amount of solute dissolves in a solvent.

What is Solubility? How does temperature affect solubility? Solubility curves are used to show how the solubility of a substance changes with temperature.

Solubility Curve

Homework Ch 12.2 pg 426 #7-12

What do you think determines the concentration of a solution? Do Now

Ch 12.3 Concentrations of Solutions

Essential Question Given the mass of the solute and the volume of the solvent, how can you calculate the concentration of a solution?

Concentrations of Solutions Solutions can be dilute; Solutions can be concentrated; A small amount of solute in the solvent A large amount of solute in the solvent

Concentration of Solutions The concentration of a solution is not based on the saturation of the solution.

Molarity Molarity (M): the number of moles of solute dissolved in one liter of solution. Note: it is the total volume in liters of solution, not the liters of solvent.

Molarity Example of Molarity: A one molar solution (1M) of NaOH contains one mole of NaOH in every liter of solution. To make a 1M solution, you must know the molar mass of the solute. Ex: one mole NaOH has 40.0g; dissolved in enough water to make 1 L, this would make a 1 M solution. 20.0g dissolved in enough water to make 1 L, would make a 0.5 M solution 80.0 g dissolved in enough water to make 1L, would make a 2M solution.

Practice How would you make the following solutions:- a)1M NaCl solution b)3 M HCl solution c)0.5 M KI solution

Relationship between Molarity, Moles, and Volume Manipulate the formula to find the missing variable.

Practice You have 3.50L of solution that contains 90.0g of sodium chloride, NaCl. What is the molarity of that solution? MNaCl

Practice You have 0.8L of a 0.5M HCL solution. How many moles of HCl does this solution contain? 0.4 molHCl

……and more practice You have 5L of a 6.0M K 2 CrO 4 solution. What volume of the solution is needed to give you 23.4g K 2 CrO 4 ? L K 2 CrO 4

Do Now Textbook Page 421 Practice problems 1,2,3. Homework Page 426 #15,16,19,20,21,22, and 23

Do Now What components are changed and unchanged in a diluted solution?

Dilutions Essential Question: How can you determine the amount of solvent needed to prepare a requested dilution?

Dilutions What components are changed and unchanged in a diluted solution? ChangedUnchanged Volume(water,solvent) Concentration (M) Solute (grams, moles)

Preparing Dilutions What is the relationship between concentration(M) and volume(V)? Indirect relationship M 1 V 1 =M 2 V 2

Practice How many milliliters of aqueous 2.00M MgSO 4 must be diluted with water to prepare 100.0mL of aqueous 0.400M MgSO 4 ? 20.0mL

Practice How many milliliters of a solution of 4.00M KI are needed to prepare 250 mL of 0.760M KI? 47.5 mL

Practice How could you prepare 250mL of 0.20M NaCl using only a solution of 1.0M NaCl and water? V1= 50 mL Transfer 50 mL to the 250mL flask, then fill it to the mark.

Do Now Describe how you would make a 2.0M AlCl 3 solution.

Molality Another way to express solution concentration is Molality (m) Another way to express solution concentration is Molality (m) NOT THE SAME AS MOLARITY! NOT THE SAME AS MOLARITY! Molality (m) is the concentration of a solution expressed in moles of solute per kilogram solvent. Molality (m) is the concentration of a solution expressed in moles of solute per kilogram solvent.

Mmmmmmmm…. How do the formulas of molarity and molarity differ, and how are they the same?

Calculate the molality of a solution prepared by dissolving 10.0g of NaCl in 600.g of water. Calculate the molality of a solution prepared by dissolving 10.0g of NaCl in 600.g of water. Calculating Molality of a Solution m = mol of solute kg of solvent kg of solvent 10.0g NaCl  mol NaCl = mol of NaCl kg of water kg of water g  kg = m NaCl

Practice What is the molality of a solution in which 0.32 moles AlCl 3 has been dissolved in 2,200 g water? 0.15m

Practice What is the molality of a solution in which mol CO 2 (44.01g/mol) is dissolved in 591 g water? 0.25m

Practice What mass of water is needed to prepare a 1.20 molal solution using 0.60 mol propyleneglycol? 0.500kg H2O

Why Use Molality VS Molarity Molality is not affected by temperature unless the solvent is water. Molality is used to study colligative properties of a solution.( boiling point, freezing point) The mass of the solvent(unless it is water) does not change. Any type of solute/solvent interaction is a colligative property.

Colligative Properties of Solutions Colligative properties depend on the concentration of the solute particles, not on the identity. Some colligative properties include:- Vapor pressure lowering Freezing point depression Boiling point elevation Osmotic Pressure

Vapor Pressure Lowering As solute particles increase/water molecules decrease Less water molecules to enter the vapor phase Vapor pressure of solution is less than that of pure water.

Freezing Point Depression The freezing point of a non electrolyte solute in water is C lower than that of freezing water. Molal freezing point constant(K f )- the freezing point depression of the solvent in a 1 molal solution. Each solvent will have it’s own constant Freezing point depressing( t f ), the difference between the freezing points of the pure solvent and a solution of a nonelectrolyte in that solvent

Practice Page 449, sample problems C and D. Classwork: Page 450, practice problems 1-4.

Do Now Think of a practical application of freezing point depression. Be prepared to explain it and discuss it with the class.

Boiling Point Elevation Solute particles decrease the amount of water Less water makes less vapor pressure More energy is required to raise the vapor pressure Boiling point of a solution is higher than that of the pure solvent