Understanding Solutions and Solubility

1. UNIT 10: SOLUTIONS AND SOLUBILITY

2. Introductions to Solutions! 1. Solution: 2. Solute 3. Solvent 4. Saturated: 5. Unsaturated:

3. 6. Supersaturated: 7. Electrolyte: 8. Aqueous: 9. Homogeneous: 10. Heterogeneous :

4. AIM# 1: How can we describe solutions? A mixture is Mixtures can be put into two categories: • Heterogeneous These mixture can contain an insoluble solid, large particles and can be separated by filtration They are meaning they do not mix and do not dissolve

5. 2. Homogeneous (also called solutions) These mixtures can be clear, colored, small particle size, and found in any pahse of matter. They are meaning one substance can dissolve in another.

6. Types of Solutions Solids: consist of most solids dissolved in solid. Can also be a liquid or gas dissolved in a solid • Examples: • Liquids: has to consist of a solute, which can be a solid, liquid, or gas dissolved in a solvent Solute: Solvent:

7. **** Solutions will take the phase of the solvent Aqueous: Examples Gases: have completely dissolved in one another • In air, what is the solute and solvent?

8. http://www.youtube.com/watch?v=xdedxfhcpWo&feature=related http://www.youtube.com/watch?v=7PHhBBg-6X0&feature=related

9. AIM# 2: What are some factors that affect solubility? 1. Nature of the Solute • Not all solutes will dissolve to the same extent as H2O • Each solute will have a different solubility • Particle size of the solute and stirring can also factor into the rate of dissolving

10. Nature of the Solute Examples: PbCl2 1g/100g H2O @ 25C ZnCl2 200g/100g H2O @ 25C

11. LIKE DISSOLVES LIKE RULE

12. 2. TEMPERATURE • Solid Solutes – as temperature increases, Solubility increases • Liquid Solutes – as temperature increases, Solubility increases • Gas Solutes – as temperature increases, Solubility decreases

13. 3. PRESSURE • Solid and liquid solutes – pressure has • For gases dissolved in liquids : Applying the principles of solubility and pressure, explain why soda goes flat when you open the can.

14. Critical thinking: A student was working in a lab. Grease spilled all over his hands. He went to the sink to clean his hands. The grease, which was non polar, did not come off. Once the student used soap and water, all of the grease came off. EXPLAIN

15. AIM#3 : How can we identify types of solutions? • Solubility: how much solute is dissolved in a given amount of solvent • Solubility is measured in grams of solute per 100 grams of solvent (mostly water) • Solubility must always be accompanied by a temperature NaCl 36g/100g H2O @ 25C

16. Saturated: • Unsaturated: • Supersaturated:

17. The solution is : On the curve __________ Under the curve ___________ Above the curve _________

18. Using Reference Table G • Up curves represent salts The relationships is direct as T increase, solubility increase • Down curves represent gases The relationship is indirect As T increase, solubility decreases

19. Each line represents a saturated solution of a solute at different temperatures • Higher a line is at a given temperature the more soluble that substance is • Data tells us how many grams of solute can be dissolved in 100g of water a particular temperature

20. View video on Solutions and Solubility: http://www.youtube.com/watch?v=VTmfQUNLlMY

21. Aim # 4 To understand concentrations of solutions using table F Dilute Concentrated

22. Concentration is directly related to the amount of solute we use Most concentrated solutions can be Least concentrated solutions can be **if something doesn’t dissolve, it will not add to the concentration of the solution.

23. Using Table F: • “Cross out the first part of the compound” (In this example it would be Li) • Find the second part of the compound on table F (CO3) • Determine the solubility and look for exceptions • Use the state of matter symbol (s) or (aq) Li2CO3 Fe(OH)3 CaCrO4 BaS

24. AIM # 5: How can we determine the concentration of solutions? Concentration: the amount of the solute dissolved in the solution. For solutions there are several ways to express concentration : • Grams of solute/100mL of solvent (TABLE G) • Molarity • Parts per million • % by mass • % by volume

25. _______________(M) moles of solute dissolved per liter (L) of solution. Must always calculate total moles in the solution • Formula

26. What is the molarity of a solution that contains 4.0 moles of NaOH in 0.50 L solution? • What is the concentration of a solution made by dissolving 175.5 grams of NaCl in enough water to make 2.00 liters of solution?

27. Percent by Mass • The mass of the part dissolved in total solution • Formula • What is the percent by mass of sodium hydroxide if 5.00g of NaOH are added to 50.00g of H2O?

28. Percent by Volume • Liters of solute dissolved in total solution • Formula • % by volume is the ratio of the volume of an ingredient divided by the total volume and expressed as a percent • What is the percent by volume of alcohol if 50mL of ethanol is diluted with water to form a total volume of 3000mL

29. How many grams of K2SO4 would you need to prepare 1500 grams of a 5% by mass solution? • What is the percent by volume of a solution containing 50 mL of diethyl either of a solution? • Calculate the grams of solute needed to make 2500 grams of saline solution for .90% NaCl by mass • What is the concentration in % volume of 125 mL of isopropyl alcohol diluted with water to a total volume of 275 mL?

30. Parts per million • We use molarity for solutions with relatively larger concentration of solute, we will use ppm to express much smaller concentrations. • This is useful to determine the amount of pollutants in the air • Formula

31. Applications of PPM • Ca 420ppm – stable concentration in sea water • Phosphate levels >1 ppm all coral will stop growing because Ca bonds to phosphate • Sharks can detect fractions of ppm of blood

32. Carbon dioxide has a solubility of 0.0972g/100g H2O @40dC. Expressed in parts per million this concentration is closest to what value? • Approximately 0.0043 grams of oxygen can be dissolved in 100.0 mL of water at 20dC. Express this in ppm • The solubility of NaCl is 284 grams in 100 grams of water. What is the concentration in ppm?

33. AIM#6: What are colligative properties and how do electrolytes affect them ? Colligative property  physical properties of solutions that depend on the concentration/ # of particles of solute in a given amount of solvent Electrolyte

34. When any pure solvent forms a solution two things occur: • Boiling point elevation = boiling point when a solute is added example: 2. Freezing point depression= freezing point when a solute is added example:

35. There is a misconception about putting salt in pot of water to make water boil faster for pasta – • When you add salt to water it takes longer to boil it increases the melting point the water will boil at a higher temperature causing the pasta (or food) to cook faster • Ocean has a lower freezing point because of salt – fresh water will freeze faster • Put salt on the roads before a snow storm so that the snow wont freeze – lowers the freezing point of the snow • If you add salt to a glass of ice– glass will feel cold – don’t do it in your hands get instant frost bite this is a similar process to making ice cream

36. The measure of changes in boiling point and freezing point are dependent on: • Solute (electrolyte vs. nonelectrolyte) • Number of particles in solution • Concentration

37. ELECTROLYTES • Ionic substances (salts) • Acids (HX) • Bases (MOH) NON-ELECTROLYTE • Sugars (C6H12O6) • Alcohols R-OH • Summary • Electrolytes conduct and turn a light bulb tester on. When placed in aqueous solutions electrolytes dissociate, ionize or break apart • None electrolytes do not conduct, do not dissociate, ionize or break apart

38. The higher the concentration of solute is, the higher the boiling point and the lower the freezing point will be: 1. Which of the following solutions will boil at the highest temperature? a.100g NaCl in 1,000g of water c. 100g NaCl in 500g of water b.100g NaCl in 250g of water d. 100g NaCl in 125g in water 2. Which of the following solutions will boil at the lowest temperature? a. 100g NaCl in 1,000g of water b. 100g NaCl in 500g of water c. 100g NaCl in 250g of water d. 100g NaCl in 125g in water 3. Which of the following solutions will freeze at the lowest temperature? a. 100g NaCl in 1,000g of water c. 100g NaCl in 500g of water b. 100g NaCl in 250g of water d. 100g NaCl in 125g in water 4. Which of the following solution will freeze at highest temperature? a. 100g NaCl in 1,000g of water c. 100g NaCl in 500g of water b. 100g NaCl in 250g of water d. 100g NaCl in 125g in water

39. The more particles that a solute ionizes into, the higher the boiling point and the lower the freezing point 1. Which of the following solutions will boil at the highest temperature? a. 100g C6H1206 in 500g of water c. 100g KBr in 500g of water b. 100g MgF2 in 500g of water d. 100g AgCl3 in 500g in water 2. Which of the following solutions will boil at the lowest temperature? a. 100g C6H1206 in 500g of water c. 100g KBr in 500g of water b. 100g MgF2 in 500g of water d. 100g AgCl3 in 500g in water 3. Which of the following solutions will freeze at the highest temperature? a. 100g C6H1206 in 500g of water c. 100g KBr in 500g of water b. 100g MgF2 in 500g of water d. 100g AgCl3 in 500g in water 4. Which of the following solutions will freeze at the lowest temperature? a. 100g C6H1206 in 500g of water c. 100g KBr in 500g of water b. 100g MgF2 in 500g of water d. 100g AgCl3 in 500g in water