General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 1.9 Problem Solving Chapter 1 Chemistry and Measurements © 2013 Pearson Education, Inc. Lectures

© 2013 Pearson Education, Inc. Chapter 1, Section 9 2 There are 4 steps to solving problems with conversion factors. Guide to Problem Solving Using Conversion Factors

© 2013 Pearson Education, Inc. Chapter 1, Section 9 3 If a person weighs 164 lb, what is the body mass in kilograms? Step 1 State the given and needed quantities. Analyze the Problem Step 2 Write a plan to convert the given unit to the needed unit. lb US–Metric kilograms Factor Steps to Solving the Problem GivenNeed 164 lbkilograms

© 2013 Pearson Education, Inc. Chapter 1, Section 9 4 If a person weighs 164 lb, what is the body mass in kilograms? Step 3 State the equalities and conversion factors. Step 4 Set up the problem to cancel units and calculate the answer. Steps to Solving the Problem

© 2013 Pearson Education, Inc. Chapter 1, Section 9 5 Learning Check How many minutes are 2.5 h?

© 2013 Pearson Education, Inc. Chapter 1, Section 9 6 Solution How many minutes are 2.5 h? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert the given unit to the needed unit. GivenNeed 2.5 hminutes hourminutes time factor

© 2013 Pearson Education, Inc. Chapter 1, Section 9 7 Solution How many minutes are 2.5 h? Step 3 State the equalities and conversion factors. Step 4 Set up problem to cancel units and calculate answer.

© 2013 Pearson Education, Inc. Chapter 1, Section 9 8 A rattlesnake is 2.44 m long. How many centimeters long is the snake? A cm B. 244 cm C cm Learning Check

© 2013 Pearson Education, Inc. Chapter 1, Section 9 9 A rattlesnake is 2.44 m long. How many centimeters long is the snake? Step 1 Analyze the Problem. Step 2 Write a plan to convert the given unit to the needed unit. meters metric centimeters conversion Solution GivenNeed 2.44 mcentimeters

© 2013 Pearson Education, Inc. Chapter 1, Section 9 10 A rattlesnake is 2.44 m long. How many centimeters long is the snake? Step 3 State the equalities and conversion factors. Step 4 Set up the problem to cancel units and calculate the answer. Solution 3 SF Exact Answer: B

© 2013 Pearson Education, Inc. Chapter 1, Section 9 11 Often, two or more conversion factors are required to obtain the unit needed for the answer. Unit 1 Unit 2 Unit 3 Additional conversion factors are placed in the setup to cancel each preceding unit. Using Two or More Factors

© 2013 Pearson Education, Inc. Chapter 1, Section 9 12 How many minutes are in 1.6 days? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert the given unit to the needed unit. days time time min factor 1 factor 2 Example: Problem Solving GivenNeed 1.6 daysminutes

© 2013 Pearson Education, Inc. Chapter 1, Section 9 13 How many minutes are in 1.6 days? Step 3 State the equalities and conversion factors. Step 4 Set up problem to cancel units and calculate answer. Example: Problem Solving

© 2013 Pearson Education, Inc. Chapter 1, Section 9 14 Learning Check An injured person loses pints of blood. How many milliliters of blood would that be?

© 2013 Pearson Education, Inc. Chapter 1, Section 9 15 Solution An injured person loses pints of blood. How many milliliters of blood would that be? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write a plan to convert the given unit to the needed unit. pints factor 1 factor 2 milliliters GivenNeed pintsmilliliters

© 2013 Pearson Education, Inc. Chapter 1, Section 9 16 Solution An injured person loses pints of blood. How many milliliters of blood would that be? Step 3 State the equalities and conversion factors. Step 4 Set up problem to cancel units and calculate answer.