General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 8.5 Dilution of Solutions and Solution Reactions Chapter 8 Solutions © 2013 Pearson Education, Inc. Lectures

© 2013 Pearson Education, Inc. Chapter 8, Section 5 2 Dilution In a process called dilution, a solvent, usually water, is added to a solution increasing its the volume and decreasing the concentration of the solution. One can of orange juice concentrate will make four cans of orange juice.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 3 Dilution Although the addition of solvent increases the volume, the amount of solute doesn’t change; it is the same in the concentrated solution and the diluted solution.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 4 Initial and Diluted Solutions In the initial and diluted solution,  the moles of solute are the same, and  the concentrations and volumes are related by the following equations:

© 2013 Pearson Education, Inc. Chapter 8, Section 5 5 Guide to Calculating Dilution Quantities

© 2013 Pearson Education, Inc. Chapter 8, Section 5 6 Learning Check What volume of a 2.00% (m/v) HCl solution can be prepared by diluting 25.0 mL of 14.0% (m/v) HCl solution?

© 2013 Pearson Education, Inc. Chapter 8, Section 5 7 Solution What volume of a 2.00% (m/v) HCl solution can be prepared by diluting 25.0 mL of 14.0% (m/v) HCl solution? Step 1 Prepare a table of the concentrations and volumes of the solutions. Analyze the Problem.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 8 What volume of a 2.00% (m/v) HCl solution can be prepared by diluting 25.0 mL of 14.0% (m/v) HCl solution? Step 2 Rearrange the dilution expression to solve for the unknown quantity. Step 3 Substitute the known quantities into the dilution expression and calculate. Solution

© 2013 Pearson Education, Inc. Chapter 8, Section 5 9 Learning Check What is the molarity (M) of a solution prepared by diluting 10.0 mL of 2.7 M NaOH to 60.0 mL?

© 2013 Pearson Education, Inc. Chapter 8, Section 5 10 Solution What is the molarity (M) of a solution prepared by diluting 10.0 mL of 2.7 M NaOH to 60.0 mL? Step 1 Prepare a table of the concentrations and volumes of the solutions. Analyze the Problem.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 11 What is the molarity (M) of a solution prepared by diluting 10.0 mL of 2.7 M NaOH to 60.0 mL? Step 2 Rearrange the dilution expression to solve for the unknown quantity. Step 3 Substitute the known quantities into the dilution expression and calculate. Solution

© 2013 Pearson Education, Inc. Chapter 8, Section 5 12 Solutions in Chemical Reactions When chemical reactions involve aqueous solutions, we use molarity and volume to determine the moles of the substances required or produced. Zinc reacts with HCl to produce ZnCl 2 and hydrogen gas H 2.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 13 Guide to Calculations Involving Solutions in Chemical Reactions

© 2013 Pearson Education, Inc. Chapter 8, Section 5 14 Learning Check How many liters of 3.00 M HCl are needed to completely react with 4.85 g of CaCO 3 ?

© 2013 Pearson Education, Inc. Chapter 8, Section 5 15 Solution How many liters of 3.00 M HCl are needed to completely react with 4.85 g of CaCO 3 ? Step 1 State the given and needed quantities. Analyze the Problem.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 16 Solution How many liters of 3.00 M HCl are needed to completely react with 4.85 g of CaCO 3 ? Step 2 Write a plan to calculate the needed quantity or concentration. mass molar moles mole–mole moles molarity liters of CaCO 3 mass of CaCO 3 factor of HCl HCl of HCl

© 2013 Pearson Education, Inc. Chapter 8, Section 5 17 Solution How many liters of 3.00 M HCl are needed to completely react with 4.85 g of CaCO 3 ? Step 3 Write equalities and conversion factors including mole–mole and concentration.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 18 Solution How many liters of 3.00 M HCl are needed to completely react with 4.85 g of CaCO 3 ? Step 3 Write equalities and conversion factors including mole–mole and concentration.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 19 Solution How many liters of 3.00 M HCl are needed to completely react with 4.85 g of CaCO 3 ? Step 4 Set up the problem to calculate the needed quantity or concentration.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 20 Learning Check If 22 mL of 0.10 M MgCl 2 is needed to completely react 15 mL of AgNO 3 solution, what is the molarity of AgNO 3 ?

© 2013 Pearson Education, Inc. Chapter 8, Section 5 21 Solution If 22 mL of 0.10 M MgCl 2 is needed to completely react 15 mL of AgNO 3 solution, what is the molarity of AgNO 3 ? Step 1 State the given and needed quantities. Analyze the Problem.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 22 Solution If 22 mL of 0.10 M MgCl 2 is needed to completely react 15 mL of AgNO 3 solution, what is the molarity of AgNO 3 ? Step 2 Write a plan to calculate the needed quantity or concentration. volume molarity moles mole–mole moles of MgCl 2 MgCl 2 of MgCl 2 factor of AgNO 3

© 2013 Pearson Education, Inc. Chapter 8, Section 5 23 Solution If 22 mL of 0.10 M MgCl 2 is needed to completely react 15 mL of AgNO 3 solution, what is the molarity of AgNO 3 ? Step 3 Write equalities and conversion factors including mole–mole and concentration.

© 2013 Pearson Education, Inc. Chapter 8, Section 5 24 Solution If 22 mL of 0.10 M MgCl 2 is needed to completely react 15 mL of AgNO 3 solution, what is the molarity of AgNO 3 ? Step 4 Set up the problem to calculate the needed quantity or concentration.