What is a homogeneous mixture?

1. Bell Ringer What is a homogeneous mixture?

2. Solutions JIGSAW Part 1

4. Bell Ringer Approximately 0.0043g of oxygen can be dissolved in 100.0 ml of water at 20°C. Express this in terms of parts per million.

6. Some Problems How would you describe the following solutions? a.) 30.0 g of sodium chloride in 100.0g of water at 90ºC unsaturated b.) 35.0 g of ammonia in 100.0g of water at 40ºC saturated c.) 140.0 g of sodium chloride in 200.0g of water at 10ºC supersaturated d.) What is in common with all of the compounds whose solubility curves decrease at temp. increases? they are all gases

8. Solutions SOLUTION - homogeneous mixture - the substance that does the dissolving SOLVENT SOLUTE - the substance that is dissolved

9. Solubility This graph is for 100 g of H2O SATURATED Point falls right on the line on the graph UNSATURATED Point is below the line on the graph SUPERSATURATED Point is above the line on the graph

10. Solution vs. Suspension Solution – homogeneous mixture dissolving = physical change (not a chemical change) Dissolved particles (atoms, ions or molecules) are extremely small and solutions cannot be separated by filtering. Suspension – heterogeneous mixture where some particles settle out upon standing ex. muddy water (clay & silt)

11. Tyndall Effect Light Beam Small particles (ions, molecules) in solution do notscatterthe light rays. Path of the light raysin solution arenotvisible. Suspension Solution

12. Solutions

13. Polar Water Molecules with Hydrogen Bonds = surface tension. • One water molecule H-bonds to another

14. NaCl dissolving in water

15. Hydration of Ions & Orientation of Polar Water Molecule

16. Solubility The amount of solute a solvent can dissolve in a given quantity of solvent at a specific temperature(and pressure for a gaseous solute) to make a saturated solution SATURATED The solvent dissolves the maximum amount of solute at a specific temperature On the line UNSATURATED Solvent dissolved less than the maximum amount of solute. It CAN dissolve MORE! Below the line SUPERSATURATED Solvent contains more solute than it can theoretically hold at a specific temperature & pressure Above the line

18. Bell Ringer Explain in terms of molecular polarity, if carbon dioxide gas is soluble in water.

20. Dissolution & HydrationWater is a Polar Molecule

21. Solutions

22. Rate of Solution Formation How much over time • Amount of Solute vs. Solvent – closer to saturation equals slower rate of dissolving • Stirring – increases contact/collisions between the solvent & solute which increases the rate of formation • Increase temperature – molecules gain KE, molecules move faster, increase contact/collisions which increase the rate of solution formation • Particle size – decrease size of particle, increases SA, increases contact which will increase the rate of solution formation

23. Solubility Curve Lab

24. Bell Ringer If you want to keep soda ‘fresh’ in a plastic bottle, how would you do it at home? Explain in terms of chemistry.

26. Formulas on Reference Tables Concentration • Compares/describes the amount of solute dissolved in the solvent • Subjective  • Concentrated vs Dilute • Objective  • Molarity – only in Chem • ppm – real world uses

27. Supersaturated SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways: • Warm the solvent so that it will dissolve more, then cool the solution • Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

28. Solutions of Ionic Compounds conduct electricity = Electrolytes Greater number (#) ions in solution… = greater electrical conductivity = stronger electrolyte. Electrolytes – charged particles (ions) in solution

29. 3 Types of Electrolyte Compounds Salts(ionic compounds), acids(H+) & bases(OH-) bright dim dark Solutions CH3COOH C6H12O6 KCl Salts = ionic = metal & non-metal K + (aq) & Cl -(aq) Acetic = weak acid H + & CH3COO - Covalent = no ions

30. Solutions can be dilute (weak) or more concentrated. Molarity (M) = expression of Concentration M = # moles of solute Liters of Solution If 2.0 moles are dissolved in 4.0 Liters… Molarity = 2.0 moles / 4.0 L = 0.50 M

31. Molarity Problems How would you make 1.00 L of a .770M solution of NaCl?

32. Molarity Problems How do you measure .770moles? You must convert to grams using the mole formula So now what?

33. How to make a .769M Solution Fill to Line

34. Molarity Problems You want a 2.0M solution of NaCl and you need 3.75L of this solution. How do you make it?

35. Bell Ringer How would you make 250ml of a .25M solution of ammonium chloride?

36. solvent, conc. of solute Dilutions Add more solvent to change the ratio of solute to solvent (M1)(V1)= (M2)(V2) (M1)(V1)  represents the original, more concentrated solution (M2)(V2)  represents the final concentration & volume after dilution

37. Making a Dilution • Measure the volume of concentrated solution needed • Add solvent until final combined volume is reached • Stir to mix thoroughly Make 500.0ml of a 3.0M solution from a 10.0M stock solution Calculate the amount of stock solution needed: (M1)(V1)= (M2)(V2) (10.0M)(V1)= (3.0M)(500.0ml) V1= 150.0ml Measure out 150.0ml of 10.0 M stock solution. Add 350.0ml of solvent to make a final volume of 500.0ml.

38. Colligative Properties Properties that depend onthe number of solute particlesin solution; not the nature of the particles Best example: Boiling Pt. Elevation Freezing Pt. Depression B.P. 100 C F.P. 0 C

39. Kool Aid Lab

40. Bell Ringer A soln is made by completely dissolving 90.g of KNO3(s) in a 100.g of water in a beaker. The temperature of the solution is 65ºC. • Determine the total mass KNO3(s) that settles to the bottom of the beaker when the original solution is cooled to 15ºC. • Describe what would happen if the pressure was increased.

42. Factors Affecting amount of Solute dissolved Temperature of Solvent ↑ Temperature, ↑ amount dissolved Solids and Liquids – Gases - ↑ Temperature, ↓ amount dissolved Table G  lines with downward slope Root Beer Fountain ↑ Pressure, ↑ amount dissolved for gases Pressure

44. Factors Affecting amount of Solute dissolved Nature of solute/solvent LIKE DISSOLVES LIKE • Polar solvents dissolve polar & ionic solutes. Water (polar) dissolves ionic solids and polar covalent solids. Salts (NaCl, KCl) are ionic & form aqueous solutions. • Non-polar dissolves non-polar. Oil (non-polar) and water (polar) don’t mix = immiscible. • Alcohols– dissolve polar & non-polar solutes; but not ionic solutes. Tinctures – alcohol is solvent.

45. Colligative Properties Properties that depend onthe number of solute particlesin solution; not the nature of the particles Best example: Boiling Pt. Elevation Freezing Pt. Depression B.P. 100 C F.P. 0 C

46. Vapor Pressure Defined • Vapor pressure is the pressure exerted by a vapor. • Ex  the H2O(g) in a sealed container. Eventually the air above the water is filled with vapor pushing down. As temperature , more molecules fill the air, and vapor pressure . • Yet, molecules both leave and join the surface, so vapor pressure also pushes molecules up.

47. Another Colligative Property Solute Effect on Vapor PressureVapor Pressure (V.P.)= pressure exerted by a vapor in equilibrium with its liquid (or solid)Volatile – substance has some V.P.Non-Volatile – V.P. = zero

48. Vapor Pressure Reduction As solute molecules are added to a solution, the solvent become less volatile (=decreased vapor pressure). Solute-solvent interactions contribute to this effect.

49. Bell Ringer Explain why CO2(g) is released when a bottle of soda is opened. What is the name of the acid in soda water?

50. Dissolved particles (solute = gray)occupy/prevent solvent particles from entering vapor phase.