Graphing
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Graphing
Graphing
a. Circle graph (also called pie chart)Used to show parts of a fixed whole. Usually parts are
labeled as percents with the circle representing 100%.
Graphing
b. Bar graph- good for showing quantitative data or data that you can count at exact intervals
Graphing
Line graph- good for showing relationship between two variables Independent variable is plotted on the X axis Dependent variable is plotted on the Y axisBest fit line is drawn so that as many points fall above
the line as below
Graphing
Directly related Positive slope As X increases, Y increases
Graphing
Inversely related Negative slope As X value increases, Y decreases
Reliable Measurements
Accuracy refers to the closeness of the measure value is to the accepted, or real, value.
Precision refers to how close a series of measurements are to one another.
is calculated by subtracting the value from the value.
Error is calculated by subtracting the experimental value from the accepted value.
The is the ratio of an error to an accepted value.
The percent error is the ratio of an error to an accepted value.
% error = error x 100 = accepted value – experimental
value x 100
accepted value accepted value
Example
An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.
The error: accepted value – experimental value=
13.34 – 10.95 =
An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.
The error: accepted value – experimental value=
13.34 – 10.95 = 2.39
An experiment finds the density of lead to be 10.95 g/cm3. The literature value for the density of lead is 13.34 g/cm3.
The error: accepted value – experimental value=
13.34 – 10.95 = 2.39
The % error: error x 100 = accepted value
2.39 x 100 =13.34
The error: accepted value – experimental value=
13.34 – 10.95 = 2.39
The % error: error x 100 = accepted value
2.39 x 100 = 17.9%13.34
Practice
Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?
Practice
Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?
28.9 – 27.0 =
Practice
Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?
28.9 – 27.0 = 1.90
Practice
Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?
28.9 – 27.0 = 1.901.90/27.0 x 100% =
Practice
Sara’s lab shows the atomic mass of aluminum to be 28.9. What is her percent error if the accepted value is 27.0?
28.9 – 27.0 = 1.901.90/27.0 x 100% = 7.04%
Practice
What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?
Practice
What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?
60.8 °C – 40.6 °C =
Practice
What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?
60.8 °C – 40.6 °C = 20.2 °C
Practice
What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?
60.8 °C – 40.6 °C = 20.2 °C20.2 °C / 60.8 °C x 100% =
Practice
What is the percent error in a measurement of the boiling point of bromine if the textbook value is 60.8 °C and the lab value is 40.6 °C?
60.8 °C – 40.6 °C = 20.2 °C20.2 °C / 60.8 °C x 100% = 33.2%
Birdville Dunbar
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