Chemistry 16.2 Slide 1 of 46 16.2 Concentrations of Solutions > Molarity • A dilute solution is one that contains a small amount of solute. • A concentrated solution contains a large amount of solute. Slide 2 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Molarity Molarity (M) is the number of moles of solute dissolved in one liter of solution. Slide 3 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Molarity 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. Slide 4 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Molarity Swirl the flask carefully to dissolve the solute. Slide 5 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Molarity Fill the flask with water exactly to the 1-L mark. Slide 6 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.2 Slide 7 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.2 Slide 8 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.2 Slide 9 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.2 Slide 10 of 46 © Copyright Pearson Prentice Hall Practice Problems for Sample Problem 16.2 Problem Solving 16.8 Solve Problem 8 with the help of an interactive guided tutorial. Slide 11 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.3 Slide 12 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.3 Sample Problem 16.3 Slide 13 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.3 Sample Problem 16.3 Slide 14 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.3 Sample Problem 16.3 Slide 15 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions Making Dilutions What effect does dilution have on the total moles of solute in a solution? Slide 16 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions Diluting a solution reduces the number of moles of solute per unit volume, but the total number of moles of solute in solution does not change. Slide 17 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions The total number of moles of solute remains unchanged upon dilution, so you can write this equation. M1 and V1 are the molarity and volume of the initial solution, and M2 and V2 are the molarity and volume of the diluted solution. Slide 18 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions Making a Dilute Solution Slide 19 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions 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. Slide 20 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions She then transfers the 20 mL to a 100-mL volumetric flask. Slide 21 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions Finally she carefully adds water to the mark to make 100 mL of solution. Slide 22 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Making Dilutions Volume-Measuring Devices Slide 23 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.4 Slide 24 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.4 Slide 25 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.4 Slide 26 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.4 Slide 27 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM Bell Work: What is the molarity of a 1500 ml solution composed of 5.3 moles of NaCl? Slide 28 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Percent Solutions Percent Solutions What are two ways to express the percent concentration of a solution? Slide 29 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Percent Solutions The concentration of a solution in percent can be expressed in two ways: 1. ratio of the volume of the solute to the volume of the solution 2. ratio of the mass of the solute to the mass of the solution. Slide 30 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Percent Solutions Concentration in Percent (Volume/Volume) Slide 31 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Percent Solutions Isopropyl alcohol (2-propanol) is sold as a 91% solution. This solution consist of 91 mL of isopropyl alcohol mixed with enough water to make 100 mL of solution. Slide 32 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.5 Slide 33 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.5 Slide 34 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.5 Slide 35 of 46 © Copyright Pearson Prentice Hall SAMPLE PROBLEM 16.5 Slide 36 of 46 © Copyright Pearson Prentice Hall 16.2 Concentrations of Solutions > Percent Solutions Concentration in Percent (Mass/Mass) Slide 37 of 46 © Copyright Pearson Prentice Hall 16.2 Section Quiz. Assess students’ understanding of the concepts in Section 16.2. Continue to: -or- Launch: Section Quiz Slide 38 of 46 © Copyright Pearson Prentice Hall 16.2 Section Quiz. 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. Slide 39 of 46 © Copyright Pearson Prentice Hall 16.2 Section Quiz. 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 Slide 40 of 46 © Copyright Pearson Prentice Hall 16.2 Section Quiz. 3. Diluting a solution does NOT change which of the following? a. concentration b. volume c. milliliters of solvent d. moles of solute Slide 41 of 46 © Copyright Pearson Prentice Hall 16.2 Section Quiz. 4. In a 2000 g solution of glucose that is labeled 5.0% (m/m), the mass of water is a. 2000 g. b. 100 g. c. 1995 g. d. 1900 g. Slide 42 of 46 © Copyright Pearson Prentice Hall END OF SHOW
