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Solutions

Solutions. Objectives/Warm-Up. SWBAT describe dilute, concentrated, saturated, unsaturated, and supersaturated solutions. What do the terms “concentrated” and “dilute” mean to you?. Objective/Warm-Up. SWBAT describe solutions and be able to complete molarity and dilution calcualtions.

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Solutions

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  1. Solutions

  2. Objectives/Warm-Up • SWBAT describe dilute, concentrated, saturated, unsaturated, and supersaturated solutions. • What do the terms “concentrated” and “dilute” mean to you?

  3. Objective/Warm-Up • SWBAT describe solutions and be able to complete molarity and dilution calcualtions. • How do we know if something is more or less concentrated or dilute? How could we quantify (measure) concentration?

  4. Concentrated • Look at the two bottles of laundry detergent. • Why is one bottle smaller than the other? • What does it mean that the smaller bottle is more “concentrated”? • What is the difference between the two laundry detergents?

  5. Solute-what is being dissolved • Solvent-what the solute is being dissolved in • Solution-the mixture of solute and solvent

  6. Making Kool-Aid • When you make Kool-Aid, what is the solute? • What is the solvent? • What is the solution?

  7. Making Kool-Aid • If you make a concentrated solution of Kool-Aid. • This solution has too much___________. • If you make a dilute solution of Kool-Aid. • This solution has too much ____________. • How can we use the concentrated solution of Kool-Aid to make a more dilute solution of Kool-Aid? solute solvent

  8. Saturated Solutions • Is there a limit to how much Kool-Aid or sugar we can dissolve in water? • What happens when we reach that limit? • What can we do to the solution to make more sugar dissolve? • When we can add no more solute to a solution, the solution is SATURATED.

  9. Objective/Warm-Up • SWBAT describe solutions. • What is a saturated solution?

  10. Ch. 15-SolutionsEssential Questions • What makes up a solution? • What are some different types of solutions? • How can I make a solution? • What factors affect solubility? • How can I measure or calculate the solubility or concentration of a solution?

  11. Supersaturated • http://www.pbs.org/kcet/wiredscience/video/259-dr_schrempp_s_chem_lab.html • Watch the demonstration of the crystallization of a supersaturated solution. • Supersaturated means that more solute is dissolved in the solution than should be able to dissolve at that temperature. • To make a supersaturated solution, heat the solution to get the solute to dissolve, then let it cool.

  12. Solubility Curves

  13. Objective/Warm-Up • SWBAT describe solutions and be able to complete molarity and dilution calcualtions. • How do we know if something is more or less concentrated or dilute? How could we quantify (measure) concentration?

  14. How do we measure concentration? • MOLARITY • M = moles solute/Liters of solution

  15. Showing saturated solutions • http://www.wwnorton.com/college/chemistry/gilbert2/tutorials/interface.asp?chapter=chapter_04&folder=saturated_solutions

  16. Thinking back… • What is the difference between homogeneous and heterogeneous mixtures?

  17. What is a solution? • A homogeneous mixture of two or more substances.

  18. Examples of Solutions… What are the solute and solvent for each of these solutions? • Kool-aid • Tea • Air • Soda • Brass • Steel

  19. Review from Yesterday… • Solubility: “Like Dissolves Like” • Fill out chart.

  20. Objective/Warm-Up • SWBAT solve dilution problems. • How many grams of NaCl are needed to make 250 mL of a 0.100 M solution?

  21. Volume-Measuring Devices buret pipette graduated cylinder volumetric flask

  22. How do we make solutions for the lab? • Using the following materials, predict how they might be used to make solutions with a particular molarity: balance, wash bottle, distilled water, volumetric flask. • Procedure: • Weigh solid. • Put some distilled water in volumetric flask. • Add solid and stir. • Fill water to line, mix completely.

  23. To make a 0.5-molar (0.5M) solution, first add 0.5 mol of solute to a 1-L volumetric flask half filled with distilled water. • Swirl the flask carefully to dissolve the solute. • Fill the flask with water exactly to the 1-L mark.

  24. http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/013_SOLUTFROMSOL.MOVhttp://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/013_SOLUTFROMSOL.MOV

  25. Oops, It’s too concentrated! • Our solution is too concentrated. How can we dilute the solution so that it is less concentrated?

  26. Dilution • M1V1=M2V2 • Because… the moles stay the same!

  27. Making a Dilute Solution

  28. To prepare 100 ml of 0.40M MgSO4 from a stock solution of 2.0M MgSO4, a student first measures 20 mL of the stock solution with a 20-mL pipet. • She then transfers the 20 mL to a 100-mL volumetric flask. • c) Finally she carefully adds water to the mark to make 100 mL of solution.

  29. Dilution Practice Problems

  30. 16.2 Review 1. To make a 1.00M aqueous solution of NaCl, 58.4 g of NaCl are dissolved in • a) 1.00 liter of water. • b) enough water to make 1.00 liter of solution • c) 1.00 kg of water. • d) 100 mL of water.

  31. 2. What mass of sodium iodide (NaI) is contained in 250 mL of a 0.500M solution? • a) 150 g • b) 75.0 g • c) 18.7 g • d) 0.50 g

  32. 3. Diluting a solution does NOT change which of the following? • a) concentration • b) volume • c) milliliters of solvent • d) moles of solute

  33. Objective/Warm-Up • SWBAT calculate molality and describe types of solutions. • If 10.0 grams of NaOH are dissolved in enough solvent to make 100 mL of solution, what is the molarity of the solution?

  34. Types of Solutions • Alloys-mixture of two or more metals • Miscible-mixture of two liquids that can mix in any proportion • Immiscible- liquids that cannot mix in any proportion • Aqueous- solutions with water as a solvent

  35. Types of Aqueous solutions • Electrolytes-conduct electricity in water, made primarily with ionic compounds • Non-electrolytes-do not conduct electricity in water, made primarily with covalent compounds

  36. Molality • Molality: m =moles solute/kg solvent • How is molality different than molarity? • How would these differences affect how to make a solution based on molality as opposed to molarity?

  37. To make a 0.500m solution of NaCl, use a balance to measure 1.000 kg of water and add 0.500 mol (29.3 g) of NaCl.

  38. Practice Calculations

  39. Objective/Warm-Up • SWBAT solve molarity and molality problems. • How many grams of FeCl3 are needed to make 50 mL of a 0.170 M solution?

  40. Reading Article/Discussion • Read the Article from the Washington Post. • In your group, create a chart/table/or graphic organizer (such as a Venn Diagram, concept map or web) describing how to get out different types of stains (oily, water-based, combination stains, carbohydrates, proteins, food pigments, wine stains)

  41. Why? • Write a 1-2 sentence summary explain how and/or why different cleaning methods are needed for different stains.

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