1. Chapter 1 Introduction to Chemistry 1.4 Problem Solving in Chemistry
1.1 The Scope of Chemistry
1.2 Chemistry and You
1.3 Thinking Like a Scientist
1.4 Problem Solving in Chemistry
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2. Chapter 1 Vocabulary Physical chemistry Pure chemistry
Applied chemistry
Technology

3. Physical chemistry
the area of chemistry that deals with the mechanism, the rate, and the energy transfer that occurs when matter undergoes a change

4. Pure chemistry
the pursuit of chemical knowledge for its own sake

5. Applied chemistry
research that is directed toward a practical goal or application

6. Technology
the means by which a society provides its members with those things needed and desired

7. Math Review
Rounding Numbers
A rounded number has about the same value as the number you start with, but it is less exact.
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8. Rules for Rounding Here's the general rule for rounding:
If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up.
Example: 38 rounded to the nearest ten is 40
If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down.
Example: 33 rounded to the nearest ten is 30
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9. What Are You Rounding to?
When rounding a number, you first need to ask: what are you rounding it to?
Numbers can be rounded to the nearest ten, the nearest hundred, the nearest thousand, and so on.
Consider the number 4,827
4,827 rounded to the nearest ten is 4,830
4,827 rounded to the nearest hundred is 4,800
4,827 rounded to the nearest thousand is 5,000
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10. Whole Numbers are simply the numbers 0, 1, 2, 3, 4, 5, … (and so on)
Fractions
Part of a whole, number in between two whole numbers, can also be represented as decimals Example: 5/6 or or 2.1 or 0.09
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11. Rounding and Fractions
Rounding fractions works exactly the same way as rounding whole numbers. The only difference is that you may now round to tenths, hundredths, thousandths, and so on.
rounded to the nearest tenth is 7.8
rounded to the nearest hundredth is 1.06
rounded to the nearest thousandth is 3.879
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12. Here's a tip: to avoid getting confused in rounding long decimals.
Look only at the number in the place you are rounding to and the number that follows it. For example, to round to the nearest hundredth, just look at the number in the hundredths place—8—and the number that follows it—2. Then you can easily round it to 5.38.
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13. 3,849.379285461 Round the above number to the following:
nearest thousand 4,000
nearest hundred 3,800
nearest ten 3,850
nearest whole number 3,849
nearest tenth 3,849.4
nearest hundredth 3,849.38
nearest thousandth 3,
nearest millionth 3,
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14. Let’s Practice
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15. 597.352 Round to the nearest tenth A) 600 B) 597.3 C) 597.4 D) 597
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16. 45.445237 Round to the nearest ten A) 45.5 B) 45.45 C) 50 D) 45
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17. Round to the nearest hundred
Round to the nearest hundred
A) 300 B) C) D)
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18. 4444444 Round to the nearest thousandth A) 0. 4444 B) 0. 4 C) 0
Round to the nearest thousandth A) B) 0.4 C) D)
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19. 5,369.4652 Round to the nearest thousand A) 5,000.5 B) 5,000 C) 5,369.465 D) 5,400
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20. 78,363. 5528954394 Round to the nearest millionth A) 78,363
78, Round to the nearest millionth A) 78, B) 78, C) 78, D) 78,
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21. Round to the nearest whole number
35.58
Round to the nearest whole number
A) 40
B) 35.6
C) 36
D) 35
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22. $16. 32 Round to the nearest dollar A) $16. 00 B) $17. 00 C) $20
$16.32 Round to the nearest dollar A) $16.00 B) $17.00 C) $20.00 D) $10.00
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23. $826. 25 Round to the nearest tenth A) $830. 00 B) $820. 00 C) $826
$ Round to the nearest tenth A) $ B) $ C) $ D) $826.30
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24. Solving Numeric Problems
The steps for solving a numeric word problem are analyze, calculate, and evaluate.
Analyze
Evaluate 2 1 3
Calculate
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25. Solving Numeric Problems
Analyze 1
First determine where you are starting from (identify what is known) and where you are going (identify what is unknown).
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26. Solving Numeric Problems
Analyze 1
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.
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27. Solving Numeric Problems
Calculate 2
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.
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28. Solving Numeric Problems
Evaluate 3
After you calculate an answer, you should evaluate it.
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29. Solving Numeric Problems
Evaluate 3
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.
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30. Sample Problem 1.1
Estimate Walking Time
Start
Finish
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 the 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.
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31. Analyze List the knowns and the unknown.
Sample Problem 1.1
Analyze List the knowns and the unknown. 1
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
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32. Calculate Solve for the unknown.
Sample Problem 1.1
Calculate Solve for the unknown. 2
The relationship 1 mile = 10 blocks can be interpreted as “1 mile per 10 blocks.”
Divide the number of blocks to be traveled by the number of blocks in 1 mile.
1 mile
10 blocks
8 blocks  = 0.8 mile
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33. Calculate Solve for the unknown.
Sample Problem 1.1
Calculate Solve for the unknown. 2
Multiply the number of miles by the time it takes to walk 1 mile.
20 minutes
1 mile
0.8 mile  = 16 minutes
Notice how the units cancel.
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34. Evaluate Does the result make sense?
Sample Problem 1.1
Evaluate Does the result make sense? 3
The answer seems reasonable, 16 minutes to walk 8 blocks.
The answer has the correct unit.
The relationships used are correct.
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35. Matthew wants to tip 15% on his bill of $11.58.
He can estimate 10% by moving the decimal over to the left one place and round to the nearest tenth. Then figure half that amout and add it to the earlier estimation.
$ $0.60 = $1.80 is about 15% of $11.58
How would you estimate 20% of $11.58?
$1.20 x 2 = $2.40 is about 20% of $11.58
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36. The steps for solving a nonnumeric problem are analyze and solve.
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.
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37. END OF 1.4
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