 # Dilutions, Solution Stoichiometry and Titrations Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 1/1.

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Dilutions, Solution Stoichiometry and Titrations Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 1/1

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/2 Diluting Concentrated Solutions dilute solutionconcentrated solution + solvent M i V i = M f V f finalinitial Since the number of moles of solute remains constant, all that changes is the volume of solution by adding more solvent.

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/6 Diluting Concentrated Solutions Add 6.94 mL 18.0 M sulfuric acid to enough water to make 250.0 mL of 0.500 M solution. M i = 18.0 MM f = 0.500 M V i = ? mLV f = 250.0 mL = 6.94 mL 18.0 M 250.0 mL V i = MiMi Mf VfMf Vf 0.500 M = Sulfuric acid is normally purchased at a concentration of 18.0 M. How would you prepare 250.0 mL of 0.500 M aqueous H 2 SO 4 ? x Why?

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/11 Solution Stoichiometry aA + bBcC + dD Moles of A Volume of Solution of A Moles of B Volume of Solution of B Mole Ratio Between A and B (Coefficients) Molar Mass of B Molarity of A

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/12 Solution Stoichiometry H 2 SO 4 (aq) + 2NaOH(aq)Na 2 SO 4 (aq) + 2H 2 O(l) What volume of 0.250 M H 2 SO 4 is needed to react with 50.0 mL of 0.100 M NaOH? Moles of H 2 SO 4 Volume of Solution of H 2 SO 4 Moles of NaOH Volume of Solution of NaOH Mole Ratio Between H 2 SO 4 and NaOH Molarity of NaOH Molarity of H 2 SO 4

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/13 Solution Stoichiometry H 2 SO 4 (aq) + 2NaOH(aq)Na 2 SO 4 (aq) + 2H 2 O(l) 2 mol NaOH 1 mol H 2 SO 4 0.250 mol H 2 SO 4 1 L solution 1 L 0.100 mol 1 L 1000 mL = 0.00500 mol NaOH Volume of H 2 SO 4 needed: 1000 mL 1 L 10.0 mL solution (0.250 M H 2 SO 4 ) 0.00500 mol NaOH 50.0 mL NaOH Moles of NaOH available: x x x xx

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/25 Titration How can you tell when the reaction is complete? HCl(aq) + NaOH(aq)NaCl(aq) + 2H 2 O(l) Titration: A procedure for determining the concentration of a solution by allowing a carefully measured volume to react with a solution of another substance (the standard solution) whose concentration is known. Once the reaction is complete you can calculate the concentration of the unknown solution.

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/26 Titration unknown concentration solution Erlenmeyer flask buret standard solution (known concentration) An indicator is added which changes color once the reaction is complete

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/31 Titration HCl(aq) + NaOH(aq)NaCl(aq) + 2H 2 O(l) 48.6 mL of a 0.100 M NaOH solution is needed to react with 20.0 mL of an unknown HCl concentration. What is the concentration of the HCl solution? Moles of NaOH Volume of Solution of NaOH Moles of HCl Volume of Solution of HCl Mole Ratio Between NaOH and HCl Molarity of HCl Molarity of NaOH

Copyright © 2008 Pearson Prentice Hall, Inc.Chapter 3/32 Titration HCl(aq) + NaOH(aq)NaCl(aq) + 2H 2 O(l) 20.0 mL solution 0.00486 mol HCl = 0.243 M HCl Concentration of HCl solution: Moles of NaOH available: 1 L 0.100 mol = 0.00486 mol NaOH 48.6 mL NaOH 1000 mL 1 L Moles of HCl reacted: 1 mol NaOH 1 mol HCl = 0.00486 mol HCl 0.00486 mol NaOH 1 L 1000 mL x x x x

H12 – C3 3.19, 3.20, 3.22, 3.87*, 3.89, 3.91*, 3.93*, 3.120*