5.-Solutions-2-1.pptx chemistry yessssss

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1. THE CHEMISTRY OF

2. A solution is a mixture of 2 or more substances in a single phase. One constituent is usually regarded as the and the others as .

3. Solutions are homogeneous mixtures of two or more pure substances. In a solution, the solute is dispersed uniformly throughout the solvent .

4. SOLUTE – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) IDENTIFYING COMPONENTS OF SOLUTIONS Solution Solute Solvent Air in balloon O 2 N 2 Ammonia water NH 3 H 2 O Rubbing alcohol (70%) H 2 O I sopropyl alcohol al Rubbing ) cohol (40% E thyl alcohol H 2 O Tincture of Iodine Iodine Alcohol Sea water Salt H 2 O

5. Gas Liquid Solid

6. SOLUTION SOLUTE SOLVENT EXAMPLE Gas in a gas Oxygen Nitrogen Air Gas in a liquid CO 2 H 2 O Soda water Liquid in a liquid Acetic acid H 2 O Vinegar Solid in a liquid Sugar H 2 O Sugar syrup Liquid in a solid Hg Ag Dental am a l g am Solid in a solid tin copper Bronze

7. Solvent molecules are attracted to surface ions. Each ion is surrounded by solvent molecules. Enthalpy ( H) changes with each interaction broken or formed. Ionic solid dissolving in water

8. The ions are solvated (surrounded by solvent). If the solvent is water, the ions are hydrated . The intermolecular forces .

9. solvation is an interaction of a solute with the solvent, which leads to stabilization of the solute in the solution.

10. Dilute Concentrated

11. Hypotonic (lower solute concentration) to the solution Hypertonic (higher solute concentration) to the solution

12. Isotonic solutions are equal in their solute concentrations.

13. It is the process by which a solid, liquid or gas forms a solution in a solvent .

14. In solids this can be explained as the breakdown of the crystal lattice into individual ions, atoms or molecules and their transport into the solvent.

15. For liquids and gases, the molecules must be compatible with those of the solvent for a solution to form.

16. Dissolution is a physical change — you can get back the original solute by evaporating the solvent. If you can’t, the substance didn’t dissolve, it reacted . Ni(s) + HCl (aq) NiCl 2 (aq) + H 2 (g) NiCl 2 (s) d ry

17. It refers to the maximum amount of solute, expressed in grams, that can be dissolved in 100 g of water at a specific temperature & pressure.

18. Soluble a substance that dissolves in a solvent Insoluble a substance that does not dissolve in a solvent (sand is insoluble in water)

19. SUBSTANCES KEROSENE OIL ETHYL AL C O H OL WATER Sugar Salt Detergent Powdered chalk Powdered charcoal Sulfur powder CuSO 4 KMnO 4 Activity: Solubility

20. Immiscible Two liquids that are insoluble Miscible Two liquids that are soluble in each other SOLVENT WATER KEROSENE ACETONE ALCOHOL oil

21. Types of Saturation Kinds of Saturation Definition Saturated Solution A solution with solute that dissolves until it is unable to dissolve anymore, leaving the undissolved substances at the bottom. Unsaturated Solution A solution (with less solute than the saturated solution) that completely dissolves, leaving no remaining substances. Supersaturated Solution A solution (with more solute than the saturated solution) that contains more undissolved solute than the saturated solution because of its tendency to crystallize and precipitate.

22. Example 1: Saturated Solution

23. Everyday Examples of Saturated Solutions Carbonated water is saturated with carbon, hence it gives off carbon through bubbles. Adding sugar to water until it no longer dissolves creates a saturated solution. Continuing to dissolve salt in water until it will no longer dissolve creates a saturated solution. The Earth's soil is saturated with nitrogen. Mixing powdered soap into water until it will not dissolve creates a saturated solution. In beer or sparkling juices there is a saturation of carbon dioxide that is let off as a gas. Coffee powder added to water can create a saturated solution. Salt added to vinegar can create a saturated solution when the salt no longer dissolves. Chocolate powder added to milk can create saturation at the point that no more powder can be added.

24. Everyday Examples of Saturated Solutions Sugar dissolved into vinegar until it will no longer do so creates a saturate solution. Water can be saturated with juice powder to create a beverage. Milk can be saturated with flour at which point no more flour can be added to the milk. Melted butter can be saturated with salt when the salt will no longer dissolve. Bathing salts can saturate water when there is no more ability to dissolve them. Sugar can be added to milk to the point of saturation. Processed tea powders can be added to water to saturate the water. Protein powder could be used to create a saturated solution with milk, tea, or water. Laxative powders could saturate juice or water with which they are mixed. Cocoa powder could be mixed into water to the point of saturation. Sugar could be mixed into tea to the point that the tea is saturated. Coffee can be saturated with sugar when no more will mix in to the coffee.

25. Example 2: Unsaturated Solution

26. Example 3: Supersaturated Solution

27. Chemists use the rule of the THUMB “like dissolves like” Polar substances tend to dissolve in polar solvents. Nonpolar substances tend to dissolve in nonpolar solvents. Nature of Solute and Solvent

28. SOLVENT NaCl C 12 H 22 O 11 C 10 H 8 I 2 Water SOLVENT WATER KEROSENE ACETONE ALCOHOL Oil Examples

29. Effect of Temperature Generally, the solubility of solid solutes in liquid solvents increases with increasing temperature.

30. SOLUTE COLD W A T E R HOT W A T E R Salt Sugar KNO 3

31. The opposite is true of gases. Higher temperature drives gases out of solution. Carbonated soft drinks are more “bubbly” if stored in the refrigerator. Warm lakes have less O 2 dissolved in them than cool lakes.

32. Effect of Pressure Small changes in pressure have little effect on the solubility of solids in liquids or liquids in liquids but have a marked effect on the solubility of gases in liquids.

33. States that: Henry’s Law

34. S g = kP g Where: S g is the solubility of the gas; k is the Henry’s law constant for that gas in that solvent; P g is the partial pressure of the gas above the liquid.

35. The larger the molecules of the solute are, the larger is their molecular weight and their size. It is more difficult for solvent molecules to surround bigger molecules. If all of the above mentioned factors all excluded, a general rule can be found that larger particles are generally less soluble . If the pressure, and temperature are the same than out of two solutes of the same polarity, the one with smaller particles is usually more soluble.

36. SOLVENT REFINED SALT ROCK SALT Water SOLVENT RE F INED KNO 3 KNO 3 C R YS T ALS Water

37. Stirring only increases the speed of the process - it increases the movement of the solvent that exposes solute , thus enabling solubility. As molecules in liquid substances are in constant move, the process would take place anyway, but it would take more time.

38. SOLUTE SET-UP W/ S T IR R ING U N DIS T U R BED SET-UP TIME TO DIS S O L VE CuSO 4 KNO 3

39. The stronger the intermolecular attractions between solute and solvent, the more likely the solute will dissolve. Example: ethanol in water Ethanol = CH 3 CH 2 OH Intermolecular forces = H-bonds; dipole- dipole; dispersion Ions in water also have ion-dipole forces.

40. Concentrations of Solutions There are a number of ways to express the relative amounts of solute and solvent in a solution. Percent Composition (by mass) Molarity Molality Mole Fraction

41. Percent Composition (by mass) We can consider percent by mass (or weight percent, as it is sometimes called) in two ways: The parts of solute per 100 parts of solution. The fraction of a solute in a solution multiplied by 100.

42. Percent Composition (by mass) We need two pieces of information to calculate the percent by mass of a solute in a solution: The mass of the solute in the solution. The mass of the solution.

43. Percent Composition (by mass) Use the following equation to calculate percent by mass:

44. Percent Composition (by mass) Examples: What is the percent by mass of rubbing alcohol in a solution that contains 275 g of rubbing alcohol in 500 g of solution? Solution: Percent by mass = mass of rubbing alcohol mass of solution = 275g 500g  = 55.0 % (m/m) x 100% x 100%

45. Percent Composition (by mass) Examples: What is the weight percent of sodium chloride in a solution that is made by dissolving 12.0g of NaCl in 60.0g of H 2 O? Solution: g solute (NaCl) = 12.0 g g solvent (H2O) = 60.0 g g solution = 72.0 g Percent by mass = 12.0 g NaCl 12.0 g + 60.0 g = 12 g 72 g  = 16.0 % NaCl solution x 100% x 100%

46. Molarity Molarity tells us the number of moles of solute in exactly one liter of a solution. (Note that molarity is spelled with an "r" and is represented by a capital M.) We need two pieces of information to calculate the molarity of a solute in a solution: The moles of solute present in the solution. The volume of solution (in liters) containing the solute.

47. Molarity To calculate molarity we use the equation:

48. 1. Sea water contains roughly 28.0 g of NaCl per liter. What is the molarity of sodium chloride in sea water? Molarity Examples

49. 2. What is the molarity of 245.0 g of H 2 SO 4  dissolved in 1.000 L of solution? Molarity Examples

50. Molality Molality, m, tells us the number of moles of solute dissolved in exactly one kilogram of solvent. (Note that molality is spelled with two " l"'s and represented by a lower case m.) We need two pieces of information to calculate the molality of a solute in a solution: The moles of solute present in the solution. The mass of solvent (in kilograms) in the solution.

51. Molality To calculate molality we use the equation:

52. Problem #1:  What is the molality pf a 0.500M aqueous solution of sucrose (C 12 H 22 O 11 ) if the density of the solution is 1.0638 g/mL? Molality Examples

53. Problem #2 : A sulfuric acid solution containing 571.4 g of H 2 SO 4  per liter of solution has a density of 1.329 g/cm 3 . Calculate the molality of H 2 SO 4  in this solution Molality Examples

54. Normality Normality of a solution is the concentration expressed as the number of gram equivalent weights (or number of equivalents, abbreviated equiv ) of solute per liter of solution. A one-normal (1 N) solution contains one gram equivalent weight of solute per liter of solution. The equivalent weight is the weight of a substance that will react with, combine with, contain, replace, or in any other way be equivalent to, one mole of hydrogen atom or hydrogen ion or hydroxide ion.

55. Normality To calculate normality we use the equation: N = no. of equivalents of solute L of solution

56. Normality Examples: Problem 1. What is the normality of a solution containing 7.00g H 3 PO 4 in 400mL of solution.