Solutions

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

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

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

4. 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 Components of Solutions

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

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

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

8. 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 Types of Solutions

9. 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) Types of Solutions

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

11. 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) Types of Solutions

12. Concentrated vs. Dilute How much solute is in the solution? Concentration – a measure of the amount of solute dissolved in a given amount of solvent or solution

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

14. 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

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

16. What is the molality of a solution containing 125 g of I2 and 750 g of CCl4? 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 Concentration of Solutions

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

18. A mixture contains 50.4 g of N2O and 65.2 g of O2 gas. What is the mole fraction of N2O? 1. Convert both values to moles 2. Add the moles to get total moles of solution 3. Divide moles of N2O by total number of moles Concentration of Solutions

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

20. 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 Solutions

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

22. 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 Solutions

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

24. 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 Solutions

25. Solubility expressed in grams per 100 grams of solvent at a specific temperature and pressure Ex. 110 grams of KNO3 in 100 grams of H20 is a saturated solution at 60oC Solutions - Solubility

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

27. 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 Solutions - Solubility

28. Solutions - Solubility

29. Solubility Curve for solids in 100g of water Solutions - Solubility

30. 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 Solutions - Solubility

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

32. 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 Solutions – Rates of Dissolving Sugar cubes

33. 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 Solutions – Rates of Dissolving

34. 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 Solutions – Rates of Dissolving Hot Tea vs. Iced Tea

35. 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 Solutions – Colligative Properties

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

37. 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 Solutions – Colligative Properties

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

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

40. 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 Solutions – Colligative Properties