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Do Now

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.

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Do Now

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  1. 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.

  2. Ch 12.1 Types of Mixtures

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

  4. 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

  5. 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,

  6. 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.

  7. Solute and Solvent Can you separate a solution? How?

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

  9. 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.

  10. 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

  11. Colloids

  12. 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

  13. 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.

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

  15. Ch 12.2 The Solution Process

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

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

  18. 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.

  19. 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

  20. 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.

  21. 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

  22. 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

  23. 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.

  24. 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.

  25. 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.

  26. 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. CuSO4 . 5H2O

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

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

  29. 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

  30. 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.

  31. 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 • S1 = S2 • P1 P2 • The escape of gas from a liquid is called effervescence.

  32. 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? • P1 = 3.5 atm • S1 = 0.77 g/L • P2 = 1.0 atm • S2 = ? g/L 0.77 g/L = S2 3.5 atm 1.0 atm S2 = 0.22 g/L

  33. 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.

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

  35. Solubility Curve

  36. Homework • Ch 12.2 pg 426 #7-12

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

  38. Ch 12.3 Concentrations of Solutions

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

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

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

  42. 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.

  43. 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.

  44. Practice • How would you make the following solutions:- • 1M NaCl solution • 3 M HCl solution • 0.5 M KI solution

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

  46. Practice You have 3.50L of solution that contains 90.0g of sodium chloride, NaCl. What is the molarity of that solution? 0.440 MNaCl

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

  48. ……and more practice You have 5L of a 6.0M K2CrO4 solution. What volume of the solution is needed to give you 23.4g K2CrO4? 0.020 L K2CrO4

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

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