1 4 Problem Solving in Chemistry Chapter 1

1. 4 Problem Solving in Chemistry > Chapter 1 Introduction to Chemistry 1. 1 The Scope of Chemistry 1. 2 Chemistry and You 1. 3 Thinking Like a Scientist 1. 4 Problem Solving in Chemistry 1 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > CHEMISTRY & YOU How does having a plan make problem solving easier? Have you ever tried to solve a crossword puzzle? If you have, you may have found it helpful to develop a strategy before you begin. 2 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Skills Used in Solving Problems What is

1. 4 Problem Solving in Chemistry > Skills Used in Solving Problems Problem solving is a skill you use all the time. • A shopper must make many decisions. Some of those are based on data, like the information on a food label. • The skills you use to solve a word problem in chemistry are not that different from those you use while shopping. 4 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Skills Used in Solving Problems Effective problem solving always involves developing a plan and then implementing that plan. 5 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Effective problem solving always involves developing a plan and then A. evaluating the plan. B. doing the calculations. C. making an estimate. D. implementing the plan. 6 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Effective problem solving always involves developing a plan and then A. evaluating the plan. B. doing the calculations. C. making an estimate. D. implementing the plan. 7 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems What are the steps

1. 4 Problem Solving in Chemistry > Solving Numeric Problems • Most word problems in chemistry require math because measurement is such an important part of chemistry. • The techniques used in this course to solve numeric problems are conveniently organized into a three-step problem-solving approach. 9 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems The steps for solving a numeric word problem are analyze, calculate, and evaluate. 10 1 2 3 Analyze Calculate Evaluate Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems 1 Analyze • First determine where you are starting from (identify what is known) and where you are going (identify what is unknown). 11 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems 1 Analyze • First determine where you are starting from (identify what is known) and where you are going (identify what is unknown). • If you expect the answer (the unknown) to be a number, you need to determine what unit(s) the answer should have. • Make a plan for using what is known to arrive at the unknown. 12 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems 2 Calculate • For some problems, you will have to convert a measurement from one unit to another. • For other problems, you may need to rearrange an equation before you can solve for an unknown. 13 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems 3 Evaluate After you calculate an answer, you should evaluate it. 14 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Numeric Problems 3 Evaluate After you calculate an answer, you should evaluate it. • Is the answer reasonable? • Does it make sense? • Did you copy the data correctly? • Did you choose the right equations? • Check that your answer has the correct unit(s) and the correct number of significant figures. 15 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 1 Estimate Walking Time You are visiting Indianapolis. You decide to walk from the Indiana State Capital to the Murat Centre for an afternoon performance. According to the map, the shortest route from the capital to theater is 8 blocks. How many minutes will the trip take if you can walk 1 mile in 20 minutes? Assume that 10 blocks equals 1 mile. 16 Finish Start Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 1 1 Analyze List the knowns and the unknown. This problem is an example of a conversion problem. One unit of measure (blocks) must be expressed in a different unit (minutes). KNOWNS distance to be traveled = 8 blocks walking speed = 1 mile/20 minutes 1 mile = 10 blocks UNKNOWN time of trip = ? minutes 17 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 1 2 Calculate Solve for the unknown. Divide the number of blocks to be traveled by the number of blocks in 1 mile. The relationship 1 mile = 10 blocks can be interpreted as “ 1 mile per 10 blocks. ” 1 mile 8 blocks 10 blocks = 0. 8 mile 18 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 1 2 Calculate Solve for the unknown. Multiply the number of miles by the time it takes to walk 1 mile. 0. 8 mile 20 minutes = 16 minutes 1 mile Notice how the units cancel. 19 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 1 3 Evaluate Does the result make sense? • The answer seems reasonable, 16 minutes to walk 8 blocks. • The answer has the correct unit. • The relationships used are correct. 20 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Matthew has been collecting quarters in a jar. He has 176 quarters. What is the value of the coins in his jar? 21 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Matthew has been collecting quarters in a jar. He has 176 quarters. What is the value of the coins in his jar? 176 quarters 1 dollar = 44 dollars 4 quarters 22 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Nonnumeric Problems What are the steps

1. 4 Problem Solving in Chemistry > Solving Nonnumeric Problems Not every word problem in chemistry requires calculations. • Some problems ask you to apply the concepts you are studying to a new situation. • You still need to identify what is known and what is unknown. • You still need to make a plan for getting from the known to the unknown. 24 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Solving Nonnumeric Problems The steps for solving a nonnumeric problem are analyze and solve. 25 1 2 Analyze Solve Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > CHEMISTRY & YOU Pick a game you like to play or a type of puzzle you enjoy solving. How does having a plan make playing the game or solving the puzzle easier? 26 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > CHEMISTRY & YOU Pick a game you like to play or a type of puzzle you enjoy solving. How does having a plan make playing the game or solving the puzzle easier? In solving a crossword puzzle, you may try to fill in all the “down” clues before attempting the “across” clues. Or you may first try to complete the fill-in-the-blank clues before moving on to the more difficult clues. 27 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 2 Scheduling Classes Manny needs to schedule his classes for next year. The school day is divided into seven periods, and he must take Algebra II, Art, Chemistry, English, History, and Physical Education. Using the information from the course catalog, find a way for Manny to schedule all his classes. ü Algebra II is offered during either 1 st or 2 nd period. ü Art is offered during 2 nd period only. ü Chemistry is offered during either 3 rd or 6 th period. ü English is offered during either 6 th or 7 th period. ü History is offered during either 4 th or 7 th period. ü Physical Education is offered during 4 th period only. ü Lunch is scheduled for 5 th period. 28 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 2 1 Analyze Identify the relevant concepts. • Manny must take lunch during 5 th period. • Art is only available during 2 nd period. • Physical Education is only available during 4 th period. 29 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 2 2 Solve Apply the concepts to this problem. Place lunch, Art, and Physical Education into Manny’s schedule. Manny’s Schedule 1 st period 2 nd period 3 rd period Art 4 th period 5 th period 6 th period P. E. Lunch 7 th period 30 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Sample Problem 1. 2 2 Solve Apply the concepts to this problem. Fill the remainder of the classes into Manny’s schedule. Manny’s Schedule 1 st period Algebra II 2 nd period Art 3 rd period Chemistry 4 th period 5 th period 6 th period 7 th period 31 P. E. Lunch English History Since Art is only available during 2 nd period, Manny must take Algebra II during 1 st period. Since P. E. is only available during 4 th period, he must take History during 7 th period. Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > The steps for solving a nonnumeric problem are: A. solve and evaluate. B. analyze, solve, and evaluate. C. analyze and solve. D. analyze, calculate, and evaluate. 32 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > The steps for solving a nonnumeric problem are: A. solve and evaluate. B. analyze, solve, and evaluate. C. analyze and solve. D. analyze, calculate, and evaluate. 33 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.

1. 4 Problem Solving in Chemistry > Key Concepts Effective problem solving always involves developing a plan and then implementing that plan. The steps for solving a numeric word problem are analyze, calculate, and evaluate. The steps for solving a nonnumeric problem are analyze and solve. 34 Copyright © Pearson Education, Inc. , or its affiliates. All Rights Reserved.