Solutions

1. Solutions

2. Water • Explain causes of properties of water • Matter Relationships • Esp. colloid, solution, suspension • Electrolytes • Strong vs weak • What kinds of things become electrolytes • Solution Process • General steps • Like dissolves like • Polar/ionic • Nonpolar • Pressure effect on gases • Temperature effect on solids and gases • Solubility Table • Describe the solution (100ml water and not 100ml water)

3. Matter Pure Substances Mixtures Elements Compounds Homogeneous Heterogeneous Solutions Colloids Suspensions Classification of Matter Chart? Compound Pure Substance Solution Homogenous Heterogeneous Mixture Element Colloid Suspension

4. What is a mixture? • A combination of 2 or more kinds of matter, each retains its own composition and properties • 2 types? • Homogeneous: a mixture with uniform composition (ex: salt water). • Heterogeneous: a mixture without uniform composition (ex: dirty water).

5. Solutions • A homogeneous mixture in a single phase. • Properties? • Uniform distribution of particles • Won’t settle out • Transparent • Can’t be filtered out (small particle size)

6. The Nature of Solutions • Solute: the part that gets dissolved in solutions • Solvent: the part that does the dissolving • Aqueous: (aq) a solution that contains water as the solvent • Tinctures: solutions that contains alcohol as the solvent • Examples: I2 in alcohol phenolphthalein solutions

7. Blinky • Sugar vs salt solutions • Gatorade

8. Solutions can be electrolytes or non-electrolytes. • What is an electrolyte? • Salts. Anything that dissolves in water and conducts electricity. • Solutes are classified according to whether they dissolve to form neutral molecules or charged ions. • Solutes dissolve to form: (non-electrolytes) (electrolytes)

9. Substances which form electrolytic solutions are • H = HydrogenM = MetalOH = HydroxideX = NM or P-ion • Acids HX ex: HCl, HNO3 polar • Bases MOH ex: NaOH ionic • Salts MX ex: NaCl, KBr, CaCO3 ionic

10. Strong vs Weak electrolytes? • What would make an electrolyte strong or weak?

11. Why? The solute pulls ions into solutions Strong vs. weak electrolytes Some compounds ionize / dissociate completely, while others don’t. (one way arrows!) Strong electrolyte – a compound that when dissolved/ionized, yields 100% ions.

12. Weak electrolyte • a solute that yields a relatively low concentration of ions in an aqueous solution. • HF(aq) + H2O(l) H3O+ (aq) + F-(aq) • In an aqueous solution, the majority of HF molecules are present as dissolved HF molecules. • In general, the extent to which a solute ionizes in solution depends on the bonds within the molecules of the solute and the strength of attraction to solvent molecules. • Note: If the strength of bonds in solute molecules < the attractive forces of the water dipoles, then the covalent bonds break and the molecule separates into ions.

13. 15.3 Properties of Electrolyte Solutions • Conductivity of Solutions • To compare the conductivities of strong and weak electrolytes, the conductivities of solutions of equal concentration must be compared. • So why does water that comes out of the tap conduct electricity? • It contains a high enough concentration of dissolved ions to make it a better conductor than pure water.

14. 3 Types of solutions? • Gaseous solutions - air, natural gas • Liquid solutions - vinegar (acetic acid dissolved in water); - soft drinks (solutions of a gas, CO2, dissolved in water. • Solid solutions - alloys such as sterling silver – 92%Ag, 8% Cu - white gold – gold containing nickel, tin, zinc or copper. - stainless steel

15. Suspensions • A heterogeneous mixture with large particles that settle out if given enough time • Example – a jar of muddy water

16. Colloids • Colloids contain intermediate size particles that remain in suspension because they are too small to settle out. • Example – the large particles settle out of the muddy water, but the water remains cloudy. The cloudy water cannot be filtered because the particles are too small and remain in suspension due to the constant movement of the liquid molecules. • Colloids include – mayonnaise (solid emulsion), foam, smoke (solid dispersed in gas), fog (liquid dispersed in gas) • Shows the Tyndell Effect

17. Colloids – Tyndell Effect

18. Rubbing alcohol_____ Milk_______ Chalk Dust_____ Vinegar _______ H2O2 _______ Windex ______ Gasoline _______ Mayo________ Hairspray _______ Jello _______ Mouth Wash______ 7-up _______ (if you don’t worry about having the same phase) Classify as either a solution or colloid

19. Matter Pure Substances Mixtures Elements Compounds Homogeneous Heterogeneous Solutions Colloids Suspensions Classification of Matter Chart (no notes)

20. Water • Electronegativity? • Polar molecule?

21. Difference in electronegativity leads to polar molecules • Draw water with a dipole arrow in your notes

22. Resulting Properties of Water (draw chart) • Electronegativity • Polar Molecule • H-bonds • Cohesion • Adhesion • Capillary action (colored rose vid) • Specific Heat • Surface Tension • Density (s vs l)

23. Explain the demo by using your chart • Paper towel bridge • Two holes in can • Paper clip in beaker • Boiling pt of water compared to alcohol

24. Demo • Who can dissolve a cube of sugar faster?

25. Crash Course 27 • https://www.youtube.com/watch?v=9h2f1Bjr0p4&list=PL8dPuuaLjXtPHzzYuWy6fYEaX9mQQ8oGr

26. The solution process • 2 Factors affecting the rate of dissolving? • Degree of Solubility: the amount of substance required to form a saturated solution in a certain amount of solvent at a certain temperature. • solute + solvent ↔ solution (equilibrium)

27. If you wish to dissolve a substance FASTER, you can by: • 1. crush it (increase surface area) • 2. stir it • 3. heat it • Heating it the only one that will allow one to dissolve MORE of the substance

28. Factors affecting solubility: • 1. Types of solvents and solutes –“Like dissolves like” Polar/ionicversusnonpolar water oil salt gasoline sugar Styrofoam

29. Like dissolves Like

30. Act it Out • Salt and H2O • Oil and H2O • Oil and Gasoline

31. Types of Solvents and Solutes Con’t • Ionic substances dissolve polar substances – salt dissolves in water (how?) • Non polar substances dissolve in non polar substances – fats, oils, gasoline dissolve (how?)

32. 2. Pressure (gases only) • As pressure increases, solubility increases • Graph for gases?

33. 3. Temperature • For most solids, solubility increases as temperature increases • Graph for solids: • For gases, solubility decreases as temperature increases • Graph for gases:

35. Solubility tables • Solubility Rules: • soluble (definition): more than 1 g of solute dissolves per 100 g of water • slightly soluble: between 0.1 and 1 g dissolves • insoluble: less than 0.1 g dissolves • d = decomposes ni - not isolated - not been found to form

36. What does it mean for a solution to be saturated? • Unsatured? • Saturated with extra solute? • Super satruated?

37. Saturated Solutions • Holds as much solute as it can at a given temperature and certain amount of solvent. • Temperature must be stated when determining solubility. • For gases, pressure must also be stated when determining solubility.

38. Unsaturated Solution • The solution is currently dissolving less than the maximum amount of solute at a given temperature. Supersaturated Solution • The solution currently holds more than the maximum amount of solute at a given temperature. • How is this possible? These solutions are created by saturating a hot solution and allowing it to cool undisturbed.

39. Solubility Problems • Ex1: What is the solubility of potassium chlorate at 50.0 oC in 100.0 ml of water? • 20.0 g of potassium chlorate in 100.0 grams of water • Ex2: What temperature will result in a saturated solution of 80.0 grams of sodium nitrate and 100.0 grams of water? • 10.0 oC

40. Solubility Problems • Ex3: If 40.0 grams of ammonium chloride are placed in 100.0 grams of water at 50.0 oC, is the solution saturated, saturated with extra solute or unsaturated? If extra solute, how much salt remains undissolved? If unsaturated, how much more salt can be dissolved? • The solution is unsaturated and can hold 10.0 more grams of ammonium chloride • Ex4: If 80.0 grams of potassium nitrate are placed in 100.0 grams of water at 44.0°C, is the solution saturated, saturated with extra solute or unsaturated? If extra solute, how much salt remains undissolved? If unsaturated, how much more salt can be dissolved? • The solution is saturated with 5.0 grams of potassium nitrate undissolved

41. Solubility Problems • Ex5: What is the solubility of ammonium chloride at 90.0 oC in 50.0 ml of water? • At this temperature the 100.0 ml of water can hold 70.0 grams of this salt. So, if half as much water is present, half as much salt will dissolve. 70.0 g = x 100.0 ml 50.0 ml • x = 35.0 grams of ammonium chloride in 50.0 grams of water

42. Solubility Problems • Ex6: What is the solubility of ammonium chloride at 50.0 oC in 200.0 ml of water? 50.0 g = x 100.0 ml 200.0 ml x = 100.0 grams of ammonium chloride in 200.0 grams of water

43. Solubility Problems • Ex7: What is the solubility of potassium chloride at 90.0 oC in 68.2 ml of water? 53.0 g = x 100.0 ml 68.2 ml x = 36.1 grams of potassium chloride in 68.2 grams of water

44. Ex8: If 140.0 grams of ammonium chloride are placed in 275 grams of water at 40.0 oC, is the solution saturated, saturated with extra solute or unsaturated? If saturated, how much salt remains undissolved? If unsaturated, how much more salt can be dissolved?

45. Ex9: If 60 grams of sodium chloride are placed in 175 grams of water at 80.0oC, is the solution saturated, saturated with extra solute or unsaturated? If saturated, how much salt remains undissolved? If unsaturated, how much more salt can be dissolved