1. Solutions Homogeneous - a mixture in which you can not identify the different parts, all the same phase Heterogeneous – a mixture in which you can identify different states or phases

2. Solutions Solution -- A homogeneous mixture of two or more substances in a single physical state

3. Properties of Solutions 1.Particles are very small – atoms, molecules, or ions 2.Particles are evenly distributed – uniformly spread out and intermingled

4. Properties of Solutions 3.Particles in a solution will not separate or settle out no matter how long it sits. ex. lemonade

5. Components of Solutions Solute – substance that is dissolved in the solution Solvent – substance solute is dissolved in ex. In lemonade, water is the solvent and sugar and lemon juice are solutes

6. Solutions Soluble – substance that is capable of being dissolved in a solvent (not all substances are soluble) Insoluble – substance that does not dissolve

7. Types of Solutions Solutions categorized by State of Solution Solid solutions -- typically alloys containing two or more metals (sterling silver, stainless steel, brass, bronze)

8. Types of Solutions Gaseous solutions – all mixtures of gases are solutions ex. Air is a mixture of nitrogen, oxygen, water vapor, pollutants, and other minor gases

9. Types of Solutions Liquid solutions – most familiar type of solution. May be … Gas in liquid – dissolved oxygen in water or carbon dioxide in soda Liquid in liquid – antifreeze is ethylene glycol in water

10. Types of Solutions Liquid solutions cont. miscible – the liquids can mix in any amount (water and alcohol) immiscible – liquids that can not mix in any proportions (oil and water)

11. Types of Solutions Aqueous solutions – solutions in which water is the solvent. Important to all living things abbreviated aq

12. Types of Solutions Aqueous solutions cont. Classified according to whether the solute dissolves to form ions and carries electricity Electrolyte - forms ions (ex.salt) Nonelectrolyte - no ions (ex. sugar)

13. Solutions Concentrated vs. Dilute How much solute is in the solution? Concentrated -- a lot of solute ( a brine or marinade) Dilute -- a little solute (weak tea)

14. Solutions Concentration – a measure of the amount of solute dissolved in a given amount of solvent or solution

15. Concentration of Solutions Molarity – abbrv. (M) a measure of the number of moles of solute dissolved in each liter of solution. Molarity = moles of solute liters of solution

16. Concentration of Solutions What is the molarity of a solution when 244 g of NaCl is dissolved in water to produce 1.75 L of solution? 1. convert grams NaCl to moles of NaCl 2. Divide moles NaCl by 1.75L

17. Concentration of Solutions Molality – abbrv. (m) a measure of the number of moles of solute dissolved in each kilogram of solvent Molality = moles of solute kilograms of solvent

18. Concentration of Solutions What is the molality of a solution containing 125 g of I 2 and 750 g of CCl 4 ? 1. The larger value represents the solvent - make sure it is in kilograms 2. Convert the smaller value into moles 3. Divide moles by kilograms of solvent

19. Concentration of Solutions Mole Fraction – abbrv. X (fraction) number of moles of one component divided by the total number of moles Mole fraction = Moles of component Total moles of solution

20. Concentration of Solutions A mixture contains 50.4 g of N 2 O and 65.2 g of O 2 gas. What is the mole fraction of N 2 O? 1. Convert both values to moles 2. Add the moles to get total moles of solution 3. Divide moles of N 2 O by total number of moles

21. Concentration of Solutions Mole fraction can be determined for solute or solvent X solute or X solvent The sum of mole fractions needs to equal 1

22. Solutions Saturation There is usually a limit to the amount of solute that can be dissolved in a solvent. Amount of solute that can be dissolved is affected by temperature and pressure

23. Solutions Saturated – a solution is saturated if it contains as much solute as can be dissolved, the maximum amount.

24. Solutions Unsaturated – solution contains less than the maximum amount of solute Supersaturated – solution contains a greater amount of the solute than necessary for a saturated solution

25. Solutions Solvation – dissolving process interaction between solute and solvent particles water solute Water particles separate and surround solute particles

26. Solutions Solubility Whether or not a substance will dissolve and the extent to which it dissolves will depend upon the solubility of the solute Solubility is the amount of solute that will dissolve in a specific solvent under given conditions

27. Solutions - Solubility Solubility expressed in grams per 100 grams of solvent at a specific temperature and pressure Ex. 110 grams of KNO 3 in 100 grams of H 2 0 is a saturated solution at 60 o C

28. Solutions - Solubility Factors affecting solubility 1. Nature of solute and solvent, whether they are similar or dissimilar substances *like substances dissolve like substances

29. Solutions - Solubility Factors affecting solubility 2. Temperature *Increasing the temperature reduces the solubility of gases in solution *Increasing temperature increases the solubility of most solids in solution

30. Solutions - Solubility

31. Solubility Curve for solids in 100g of water

32. Solutions - Solubility Factors affecting solubility 3. Pressure Pressure has little effect on the solubility of solids Increasing the pressure over a gas in liquid solution increase the gases solubility

33. Solutions Rate of Dissolving The rate at which a solid solute dissolves in a solution depends on three factors and is unrelated to solubility

34. Solutions – Rates of Dissolving Factors Affecting Rate of Dissolving 1. Surface Area Dissolving process occurs at the surface of the solid. Increasing the surface area by crushing the solid increases its rate of dissolving Sugar cubes

35. Solutions – Rates of Dissolving Factors Affecting Rate of Dissolving 2. Stirring Stirring or agitating the solution increases the rate of dissolving Stirring sweeps away dissolved solute particles and allows solvent to contact undissolved solute

36. Solutions – Rates of Dissolving Factors Affecting Rate of Dissolving 3. Temperature Raising the temperature increases the rate at which the solute dissolves Increased temperature means solvent particles have more energy to move and remove solute particles Hot Tea vs. Iced Tea

37. Solutions – Colligative Properties The physical properties of a liquid solution will be different than those of the pure solvent Colligative Property is a property that depends upon the concentration of the solute particles but not their identity

38. Solutions – Colligative Properties Four Colligative Properties 1. Vapor pressure reduction 2. Boiling point elevation 3. Freezing point depression 4. Osmotic pressure

39. Solutions – Colligative Properties 1.Vapor pressure reduction Vapor pressure results from liquid particles vaporizing at the surface of the liquid Solute particles crowd out solvent particles at the surface, reducing the vapor pressure

40. Solutions – Colligative Properties 2.Boiling Point Elevation Remember that boiling occurs when vapor pressure is equal to the atmospheric pressure And, vapor pressure reduction occurs in solutions

41. Solutions – Colligative Properties 2.Boiling Point Elevation (cont.) Consequently, a higher temperature is needed to get vapor pressure equal to atmospheric pressure Raising the boiling point temperature Antifreeze in autos raises the boiling pt.

42. Solutions – Colligative Properties 3.Freezing Point Depression The presence of solute particles disrupts the orderly arrangement of solvent particles as they try to solidify Lowering the freezing point temperature

43. Solutions