Mixtures and Solutions

1. Mixtures and Solutions Chemistry Matter and Change Chapter 14

2. Nearly all of the gases, liquids and solids that make up our world are mixtures. Chapter 14 Main Idea

3. Types of Mixtures Chemistry- Matter and Change 14.4

4. Mixtures can be either heterogeneous or homogeneous. 14.1 Main Idea

5. Compare the properties of suspensions, colloids and solutions • Identify the types of colloids and types of solutions • Describe the electrostatic forces in colloids • Predict whether a solution is an electrolyte or nonelectrolyte • Test your prediction 14.1 Objectives

6. Solute • Solvent • Molar mass • Concentration Review Vocabulary

7. Suspension • Colloid • Brownian motion • Tyndall effect • Soluble • Miscible • Insoluble • Immiscible • Electrolyte • Nonelectrolyte New Vocabulary

8. Heterogeneous mixtures • Mixture- a combination of two or more substances that each retain their individual chemical properties • Not the same composition throughout the substance

9. Suspensions • Type of heterogeneous mixture • Large particles settle if left undisturbed • Filter out

10. Colloids • Medium sized particles do not settle out, but remain visibly different • Cannot filter out

11. Categories of Colloids

12. Examples of Colloids

13. Brownian Motion • Movement of particles in a colloid • Erratic • Particles may repel preventing settling

14. Tyndall effect • Small particles that do not settle out • Too small to be seen unaided • Create a visible line when a laser is shined through them (scatter light)

15. Classification of Matter Solutions are homogeneous mixtures

16. Homogeneous mixtures • Solvent- material in greater quantity • Solute- material in lesser quantity • Do not disperse laser light

17. Forming solutions • Not all materials will form solutions • Soluble- the two substances will form a solution • Miscible- two liquids that will form a solution no matter their proportions (tea and water) • Insoluble- two materials that never form a solution (sand in water) • Immiscible- may be mixed, but will separate quickly (oil and vinegar)

18. Electrolytes vs. Nonelectrolytes The ammeter measures the flow of electrons (current) through the circuit. • If the ammeter measures a current, and the bulb glows, then the solution conducts. If the ammeter measures a current, and the bulb glows, then the solution conducts. If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.

19. Definition of Electrolytes and Nonelectrolytes An electrolyte is: A nonelectrolyte is: • A substance whose aqueous solution conducts an electric current. • A substance whose aqueous solution does not conduct an electric current.

20. Electrolytes? • Pure water • Tap water • Sugar solution • Sodium chloride solution • Hydrochloric acid solution • Lactic acid solution • Ethyl alcohol solution • Pure sodium chloride

21. Answers to Electrolytes ELECTROLYTES: NONELECTROLYTES: • Tap water (weak) • NaCl solution • HCl solution • Lactate solution (weak) • Pure water • Sugar solution • Ethanol solution • Pure NaCl But why do some compounds conduct electricity in solution while others do not…?

22. Comparethe properties of suspensions, colloids and solutions • Identify the types of colloids and types of solutions • Describe the electrostatic forces in colloids • Predict whether a solution is an electrolyte or nonelectrolyte • Test your prediction Can you…

23. Solution Concentration Chemistry- Matter and Change 14.2

24. Concentration can be expressed in terms of percent or in terms of moles 14.2 Main Idea

25. Describeconcentration using different units • Determine the concentration of solutions • Calculate the molarity of a solution • Prepare different solutions with given molarity, percent by mass, percent by volume, molality, and mole ratio. 14.2 Objectives

26. Solvent • Ratio • Mass • Mole Review Vocabulary

27. Concentration • Molarity • Molality • Mole fraction • Dilution New Vocabulary

28. Concentrated vs. Dilute

29. Expressing Concentration

30. Percent by mass • The mass of the solute divided by the mass of the solution

31. In order to maintain a sodium chloride concentration similar to ocean water, an aquarium must contain 3.6 g sodium chloride per 100.0 g of water. What is the percent by mass of NaCl in the solution? • Mass of solute: 3.6 g • Mass of solution: 100.0 g + 3.6 g =103.6 g • Percent by mass = (3.6g/103.6g) x 100 = 3.5%

32. Percent by volume • The volume of the solute divided by the volume of the solution

33. What is the percent by volume of ethanol in a solution that contains 35mL of ethanol distributed in 155mL of water? • Volume of solute: 35mL • Volume of solution: 155mL+35mL = 190mL • Percent by volume = (35mL/190mL) x100 = 18%

34. Molarity • Most commonly used • The moles of solute/liters of solution • Represented by M Important Notes Q: What do you call a tooth in a glass of water? A: One molar solution.

35. One way to measure the strength of a solution • moles of solute per liter of solution. You must switch all units to moles and liters! • Recall 1000 mL = 1 L Important Notes Important Notes

36. You have 3.50 L of solution that contains 90.0 g of sodium chloride, NaCl. What is the molarity of that solution? 90.0 g NaCl 1 mol NaCl = 0.440 M NaCl 3.50 L Solution 58.44 g NaCl

37. A 100.5mL intravenous solution contains 5.10g of glucose. What is the molarity of this solution? (The molar mass of glucose is 180.16 g/mol) • Moles of solute = 0.0283 mol C6H12O6 5.10 g glucose 1 mol glucose 180.16 g glucose Liters of solution = 100.5 mL 1L = 0.1005 L 1000mL Molarity = 0.0283 mol/0.1005 L = 0.282M

38. Dilution of molar solutions • M1V1=M2V2 • M is molarity; V is volume Important Notes

39. What volume in milliliters, of a 2.00M calcium chloride stock solution would you use to make 0.50 L of 0.300M calcium chloride solution? • M1=2.00M • V1=? • M2 = 0.300M • V2=0.50L • V1= 0.50L 0.300M = 0.0750L 1000mL 2.00M 1L V1=75mL

40. Molality • Used when volume of solution is highly variable due to temperature differences • The moles of solute/kg of solvent • Represented by m Important Notes

41. Molality The concentration of a solution in moles of solute per kilogram of solvent. Important Notes You must switch all units to moles and kilograms! Recall 1000 g = 1 kg Important Notes

42. In the lab, a student adds 4.5 g of sodium chloride to 100.0 g of water. Calculate the molality of the solution. • Mass of water = 100.0 g = 0.1000 kg • Mass of sodium chloride = 4.5g • Moles of NaCl 4.5g NaCl 1 mol NaCl = 0.077 mol NaCl 58.44g NaCl Molality =0.077 mol/0.1000 kg = 0.77m

43. Mole fraction • Represented by XA and XB and X… Important Notes

44. A hydrochloric acid solution contains 36g HCl and 64g H2O. What is the mole fraction for the solution? • 36g HCl = 1.0 mol HCl • 64g H2O = 3.6 mol H2O • XHCl = 0.1mol /4.6 mol = 0.22 • XH2O = 3.6 mol/4.6 mol = 0.78

45. Describe concentration using different units • Determine the concentration of solutions • Calculate the molarity of a solution • Prepare different solutions with given molarity, percent by mass, percent by volume, molality, and mole ratio. 14.2 Can you…

46. Factors Affecting Solvation Chemistry- Matter and Change 14.3

47. Factors such as temperature, pressure and polarity affect the formation of solutions 14.3 Main Idea

48. Describe how intermolecular forces affect solvation • Define solubility • Predict how different factors affect solubility • Create solutions that are unsaturated, saturated and super-saturated 14.3 Objectives

49. Exothermic • Endothermic • Solution • Polarity • Ionic bond • Covalent bond • Ionization Review Vocabulary

50. Solvation • Heat of solution • Unsaturated solution • Saturated solution • Supersaturated solution • Henry’s law • Dissociation New Vocabulary