Name ________________________________________ Class _________________ Date _______________
UNCERTAINTY IN MEASUREMENTS
3.2
SECTION REVIEW
Objectives
• Distinguish among the accuracy, precision, and error of a measurement
• Identify the number of significant figures in a measurement and in the result of a
calculation
Key Terms
• accuracy
• precision
• accepted value
• experimental value
• error
• percent error
• significant figures
Key Equations
• Error = accepted value 2 experimental value
|error|
accepted value
• Percent error = }} 3 100
Part A Completion
Use this completion exercise to check your understanding of the concepts and terms
that are introduced in this section. Each blank can be completed with a term, short
phrase, or number.
1
The
of a measurement describes how close the
2
measurement comes to the true value. The
3
ment depends on its reproducibility. A(n)
4
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measured in the lab.
dividing the
6
then multiplying by
is a value
is calculated by subtracting a
5
measurement from the
of a measure-
. Percent error is calculated by
of the error by the accepted value and
7
.
8
, plus a last digit that is
2.
3.
4.
5.
6.
7.
Significant figures in a measurement include all of the digits
that are
1.
9
.
8.
9.
Review Module / Chapters 1–4
53
Name ________________________________________ Class _________________ Date _______________
Part B True-False
Classify each of these statements as always true, AT; sometimes true, ST; or never true, NT.
________ 10. Zeros at the end of a measurement and to the left of the decimal point
are not significant.
________ 11. Significant figures include all the digits that can be known accurately plus
a last digit that must be estimated.
________ 12. An answer to calculations done with scientific measurements cannot be
more precise than the least precise measurement.
Part C Matching
Match each description in Column B to the correct term in Column A.
Column A
Column B
________ 13. accuracy
a. measure of how close a series of measurements
are to one another
________ 14. precision
b. measure of how close a measurement comes to
the actual value
________ 15. experimental value
c. digits in a measurement that are known, plus
one that is estimated
________ 16. significant figures
d. a value determined in the laboratory
Part D Questions and Problems
Answer the following questions or solve the following problems in the space provided.
Show your work.
a. 3.85 3 1023 dm
a.
b. 17.30 cm3
b.
c. 0.0037 mm
c.
18. Perform the following operations and give the answers in standard exponential
form with the correct number of significant figures.
a. 37.2 mL 1 18.0 mL 1 380 mL 5
b. 0.57 cm 3 0.86 cm 3 17.1 cm 5
c. (8.13 3 104) 4 (3.8 3 102) 5
54
Review Module / Chapters 1–4
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17. Give the number of significant figures in the following measurements