Slide 2 Slide 1 of 48 Measurements and Their Uncertainty 3.1 3.1
Section 3.1-1 Scientific Notation and % Error Slide 3 Copyright
Pearson Prentice Hall Slide 2 of 48 3.1 Measurements and Their
Uncertainty On January 4, 2004, the Mars Exploration Rover Spirit
landed on Mars. Each day of its mission, Spirit recorded
measurements for analysis. In the chemistry laboratory, you must
strive for accuracy and precision in your measurements. Slide 4
Copyright Pearson Prentice Hall Measurements and Their Uncertainty
> Slide 3 of 48 Using and Expressing Measurements How do
measurements relate to science? 3.1 Slide 5 Copyright Pearson
Prentice Hall Measurements and Their Uncertainty > Slide 4 of 48
3.1 Using and Expressing Measurements A measurement is a quantity
that has both a number and a unit. Measurements are fundamental to
the experimental sciences. For that reason, it is important to be
able to make measurements and to decide whether a measurement is
correct. Slide 6 Copyright Pearson Prentice Hall Measurements and
Their Uncertainty > Slide 5 of 48 3.1 Using and Expressing
Measurements In scientific notation, a given number is written as
the product of two numbers: a coefficient and 10 raised to a power.
The number of stars in a galaxy is an example of an estimate that
should be expressed in scientific notation. Slide 7 Copyright
Pearson Prentice Hall Measurements and Their Uncertainty > Slide
6 of 48 Accuracy, Precision, and Error How do you evaluate accuracy
and precision? 3.1 Slide 8 Copyright Pearson Prentice Hall
Measurements and Their Uncertainty > Slide 7 of 48 3.1 Accuracy,
Precision, and Error Accuracy and Precision Accuracy is a measure
of how close a measurement comes to the actual or true value of
whatever is measured. Precision is a measure of how close a series
of measurements are to one another. Slide 9 Copyright Pearson
Prentice Hall Measurements and Their Uncertainty > Slide 8 of 48
3.1 Accuracy, Precision, and Error To evaluate the accuracy of a
measurement, the measured value must be compared to the correct
value. To evaluate the precision of a measurement, you must compare
the values of two or more repeated measurements. Slide 10 Copyright
Pearson Prentice Hall Measurements and Their Uncertainty > Slide
9 of 48 3.1 Accuracy, Precision, and Error Slide 11 Copyright
Pearson Prentice Hall Measurements and Their Uncertainty > Slide
10 of 48 3.1 Accuracy, Precision, and Error Determining Error The
accepted value is the correct value based on reliable references.
The experimental value is the value measured in the lab. The
difference between the experimental value and the accepted value is
called the error. Slide 12 Copyright Pearson Prentice Hall
Measurements and Their Uncertainty > Slide 11 of 48 3.1
Accuracy, Precision, and Error The percent error is the absolute
value of the error divided by the accepted value, multiplied by
100%. Slide 13 Copyright Pearson Prentice Hall Measurements and
Their Uncertainty > Slide 12 of 48 Accuracy, Precision, and
Error 3.1 Slide 14 Copyright Pearson Prentice Hall Measurements and
Their Uncertainty > Slide 13 of 48 3.1 Accuracy, Precision, and
Error Just because a measuring device works, you cannot assume it
is accurate. The scale below has not been properly zeroed, so the
reading obtained for the persons weight is inaccurate. Slide 15
Copyright Pearson Prentice Hall Slide 14 of 48 3.1 Section Quiz 1.
In which of the following expressions is the number on the left NOT
equal to the number on the right? a.0.00456 x 10 8 = 4.56 x 10 11
b.454 x 10 8 = 4.54 x 10 6 c.842.6 x 10 4 = 8.426 x 10 6 d.0.00452
x 10 6 = 4.52 x 10 9 Slide 16 Copyright Pearson Prentice Hall Slide
15 of 48 3.1 Section Quiz 2. Which set of measurements of a 2.00-g
standard is the most precise? a.2.00 g, 2.01 g, 1.98 g b.2.10 g,
2.00 g, 2.20 g c.2.02 g, 2.03 g, 2.04 g d.1.50 g, 2.00 g, 2.50 g
Slide 17 Copyright Pearson Prentice Hall Slide 16 of 48 Thats All
Folks ! ! !
