Chapter 12 Lecture Basic Chemistry Fourth Edition Chapter 12 Solutions 12.1 Dilution and Chemical Reactions in Solution Learning Goal Calculate the new concentration or volume of a diluted solution. Given the volume and concentration of a solution, calculate the amount of another reactant or product in a reaction. © 2014 Pearson Education, Inc.

In a dilution a solvent, usually water, is added to a solution that increases the volume the concentration of the new solution will be less due to the larger volume © 2014 Pearson Education, Inc. Dilutions

© 2014 Pearson Education, Inc. In a dilution the amount of solute does not change, only the volume of the solution. C 1 V 1 = C 2 V 2 Where C is the concentration of the solution (it can be molarity or percent concentration), and V is the volume of the solution. Dilutions, Changing Volume Grams or moles of solute in concentrated solution = Grams or moles of solute in diluted solution

© 2014 Pearson Education, Inc. Dilutions, Changing Volume When water is added to a concentrated solution, there is no change in the number of particles. The solute particles spread out as the volume of the diluted solution increases.

© 2014 Pearson Education, Inc. Guide to Calculating Dilution Quantities

© 2014 Pearson Education, Inc. What is the final molarity of the solution when L of M KOH is diluted to L? Learning Check

© 2014 Pearson Education, Inc. What is the final molarity of the solution when L of M KOH is diluted to L? Step 1 Prepare a table of the concentrations and volumes. Solution

© 2014 Pearson Education, Inc. What is the final molarity of the solution when L of M KOH is diluted to L? Step 2 Rearrange the dilution expression to solve for the unknown quantity. Solution

© 2014 Pearson Education, Inc. What is the final molarity of the solution when L of M KOH is diluted to L? Step 3 Substitute the known quantities into the dilution expression and calculate. Solution

© 2014 Pearson Education, Inc. What is the volume, in milliliters, of a 5.4% (m/v) NH 3 solution that can be prepared by diluting 50.0 mL of a 15% (m/v) NH 3 solution? Learning Check

© 2014 Pearson Education, Inc. What is the volume, in milliliters, of a 5.4% (m/v) NH 3 solution that can be prepared by diluting 50.0 mL of a 15% (m/v) NH 3 solution? Step 1 Prepare a table of concentrations and volumes of the solutions. Solution

© 2014 Pearson Education, Inc. What is the volume, in milliliters, of a 5.4% (m/v) NH 3 solution that can be prepared by diluting 50.0 mL of a 15% (m/v) NH 3 solution? Step 2 Rearrange the dilution expression to solve for the unknown quantity. Solution

© 2014 Pearson Education, Inc. What is the volume, in milliliters, of a 5.4% (m/v) NH 3 solution that can be prepared by diluting 50.0 mL of a 15% (m/v) NH 3 solution? Step 3 Substitute the known quantities into the dilution expression and calculate. Solution

© 2014 Pearson Education, Inc. In a chemical reaction, the volume and molarity of a solution are used to determine the moles of a reactant or product Chemical Reactions in Solution

© 2014 Pearson Education, Inc. Guide to Calculations, Solutions in Chemical Reactions

© 2014 Pearson Education, Inc. Given the following reaction, determine how many liters of 1.50 M HCl solution completely react with 5.32 g of zinc? Zn(s) + 2HCl(aq)  H 2 (g) + ZnCl 2 (aq) Learning Check Zinc reacts when placed in a HCl solution.

© 2014 Pearson Education, Inc. Given the following reaction, determine how many liters of 1.50 M HCl solution completely react with 5.32 g of zinc? Zn(s) + 2HCl(aq)  H 2 (g) + ZnCl 2 (aq) Step 1 State the given and needed quantities. Solution

© 2014 Pearson Education, Inc. Given the following reaction, determine how many liters of 1.50 M HCl solution completely react with 5.32 g of zinc? Zn(s) + 2HCl(aq)  H 2 (g) + ZnCl 2 (aq) Step 2 Write a plan to calculate the needed quantity or concentration. Solution Grams of Zn Molar mass Moles of Zn Mole-mole factor Moles of HCl Molarity Liters of HCl

© 2014 Pearson Education, Inc. Given the following reaction, determine how many liters of 1.50 M HCl solution completely react with 5.32 g of zinc? Zn(s) + 2HCl(aq)  H 2 (g) + ZnCl 2 (aq) Step 3 Write equalities and conversion factors, including mole-mole and concentration factors. Solution

© 2014 Pearson Education, Inc. Given the following reaction, determine how many liters of 1.50 M HCl solution completely react with 5.32 g of zinc? Zn(s) + 2HCl(aq)  H 2 (g) + ZnCl 2 (aq) Step 3 Write equalities and conversion factors, including mole-mole and concentration factors. Solution

© 2014 Pearson Education, Inc. Given the following reaction, determine how many liters of 1.50 M HCl solution completely react with 5.32 g of zinc? Zn(s) + 2HCl(aq)  H 2 (g) + ZnCl 2 (aq) Step 4 Set up problem to calculate the needed quantity or concentration. Solution

© 2014 Pearson Education, Inc. Concept Map, Substance A to Substance B