1. 1 solutionscolloidssuspensions < 1 nm> 100 nm transparent with Tyndall effect (scattering of light) translucent (cloudy) molecular motionmovement by gravity coagulation – can settle never settle transparent (clear)

2. 2 solutionscolloidssuspensions < 1 nm> 100 nm Tyndall Effect? Passage of lightScattering in beam Scattering in all directions Absorption of light

3. 3 Does a chemical reaction take place when one substance dissolves in another? No, dissolving is a physical change because no new substances are formed. When one substance dissolves in another, the resulting mixture is called a solution.

4. 4 Solutions

5. 5 Does a chemical reaction take place when one substance dissolves in another? No, dissolving is a physical change because no new substances are formed. When one substance dissolves in another, the resulting mixture is called a solution.

6. 6 Some Definitions A solution is a _______________ mixture of 2 or more substances in a single phase. One constituent is usually regarded as the SOLVENT and the others as SOLUTES. HOMOGENEOUS

7. 7 Parts of a Solution The substance that is dissolved The substance present in a smaller amount The substance that dissolves the solute The substance that is present in the greater amount The solvent determines the state of the solution Solute + Solvent = Solution Solute Solvent

8. 8 “Like dissolves like” –Polar dissolves in polar and ionic Ex. Sugar and Water –Non-polar dissolves in non-polar Ex. oil and soap

9. 9 The solute breaks up into tiny particles that spread evenly throughout the solvent. In a solution of sugar water, sugar is the solute, and water is the solvent.

10. 10 Are all solutions liquids? No! Many types of solutions are possible. Let’s talk about a few examples.

11. 11 Alloy- a mixture done by the melting of two or more metals

12. 12 How do I get solutes to dissolve faster in solvents? Ex. Sugar in iced tea? Stir, and stir, and stir Add temperature Grind the solute to make it smaller Fresh solvent contact and interaction with solute Greater surface area, more solute-solvent interaction Faster rate of dissolution at higher temperature

13. 13 Definition: The maximum amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure. Soluble- the solute can be completely dissolved in the solvent Insoluble- the solute cannot be dissolved in the solvent. In fact, it separates completely. SOLUBILITY

14. 14 Miscible vs. Immiscible When two liquids totally mix they are said to be miscible. When two liquids do not mix they are said to be immiscible.

15. 15 Dissolving process in water Na + Cl - When particles of the solute are completely dispersed and surrounded by particles of the solvent, this process is called SOLVATION.

16. 16 Na + Cl - For water: POLAR-POLAR For NaCl (s): ion-ion For hydrated ion: Ion-polar The separation of the ions in an ionic compound (usually by dissolving water) is called DISSOCIATION

17. 17 The physical process of converting an atom or a compound into ions by adding or removing electrons. Usually done by a solvent in a solution. IONIZATION

18. 18 Definitions Solutions can be classified as saturated or unsaturated. A saturated solution-Contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution- Contains less than the maximum amount of solute that can dissolve at a particular temperature

19. 19 Definitions 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: 1.Warm the solvent then cool the solution 2.Evaporate some of the solvent. http://www.youtube.com/watch?v=XSGvy2FP fCw

20. 20 Supersaturated Sodium Acetate Supersaturated Sodium Acetate One application of a supersaturated solution is the sodium acetate “heat pack.”One application of a supersaturated solution is the sodium acetate “heat pack.”

21. 21 How do we know ions are present in aqueous solutions? If the solution conducts electricity it is called an ELECTROLYTE it is called an ELECTROLYTE Aqueous Solutions (water is the solvent)

22. 22 Types of solutes Na + Cl - Strong Electrolyte - 100% dissociation, all ions in solution high conductivity

23. 23 Types of solutes CH 3 COOH CH 3 COO - H+H+ Weak Electrolyte - partial dissociation, molecules and ions in solution slight conductivity

24. 24 Aqueous Solutions Some compounds dissolve in water but do not conduct electricity. They are called NONELECTROLYTES. Examples include: sugarethanol ethylene glycol Examples include: sugarethanol ethylene glycol

25. 25 Types of solutes sugar Non-electrolyte - No dissociation, all molecules in solution no conductivity

26. 26 Electrolytes in the Body  Carry messages to and from the brain as electrical signals  Maintain cellular function with the correct concentrations electrolytes Make your own 50-70 g sugar One liter of warm water Pinch of salt 200ml of sugar free fruit squash Mix, cool and drink

27. 27 Concentration The measure of how much solute is dissolved in a specific amount of solvent or solution. Concentrated  large amount of solute  high Molarity Diluted  small amount of solute  low Molarity

28. 28 Percent by Mass The ratio of the solute’s mass to the solution’s mass expressed as a percent. Percent by Mass = mass of solute mass of solution X 100

29. 29 Calculating Percent by mass What is the percent by mass of NaHCO 3 in a solution containing 20 g NaHCO 3 dissolved in 600 ml of H 2 O? % mass NaHCO 3 % mass = mass solute mass solution 20 g NaHCO 3  solute 600 ml H 2 O  solvent 1 ml H2O = 1 g H 2 O  600 g H 2 O X 100 Formula Given Implied % mass = 20g NaHCO3 620 g H2O Unknown X 100= 3%

30. 30 Your turn You have been given 3.6 g NaCl that you then dissolve in 525 g of water. What would be the percentage by mass of NaCl?

31. 31 Molarity The number of moles of solute dissolved in per liter of a solution. Molarity = moles of solute = mol liters of solution L Molarity (M) = moles solute liters of solution

32. 32 Calculating Molarity What is the molarity of an aqueous solution containing 40.0 g of glucose (C 6 H 12 O 6 ) in a 1500 ml solution? If given 340 g of CuCl 2, what would be the molarity of the solution if it was dissolved in 6425 cm 3 of water? Note: (1 cm 3 = 1 ml)

33. 33 molality Since the volume of a solution changes as temperature changes, the Molarity of the solution changes as well. Therefore, sometimes it is more useful to use molality. Note 1 Kg= 1000 g Why? Because masses do not change with temperature! Molality (m)= mol solute kilograms solvent

34. 34 Calculating molality What is the molality of a solution containing 10.0 g Na 2 SO 4 dissolved in 1000.0 g of water? What is the molality of a solution containing 30.0 g of naphthalene (C 10 H 8 ) dissolved in 500.0 g of toluene?

35. 35 Practice Problems Calculate the percent by mass of 3.55 g NaCl dissolved in 88 g water. Calculate the percent by mass of benzene in a solution containing 14.2 g of benzene in 28.0 g of carbon tetrachloride. What is the molarity of the following solutions? –15.25 g MgCl2 in 500 mL of solution –2.48 g CaF2 in 375 cm3 of solution Calculate the molality of the following solutions: –20.0 g CaCl2 in 700.0 g H2O –3.76 g NaOH in 0.850 L H2O