Mass, Volume, and Density
Mass
In science, it is important to learn about the relationships between mass, volume, and density. In order to determine mass, you will need a balance, or scale. View this interactivity to learn more about mass and how to use a triple beam balance. Make sure to complete the practice activity at the end of the interactivity.
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Volume
Volume is the amount of space an object takes up. Since every object takes up space, all objects have a volume. View this interactivity to learn more about volume, and how to calculate the volume of an object.
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Percent Error
The measurement that you, or even a professional chemist, records or calculates may not always be the same as the accepted value of that quantity. The percent error is the difference between the approximate value and the exact value, as a percentage of the exact value. The formula for this definition of percent error is:
The | symbols mean that the quantity has an absolute value, so any negative numbers automatically become positive. For more information, take a look at the example below.
Example
Pretend that you are performing a scientific investigation that involves the collection of rainwater to determine the pH of your local rain. You use a graduated cylinder to collect the rain for the experiment and your measurement of the total rainfall is 2.9 centimeters. You learn that the official measurement for that storms rainfall was 3.5 centimeters. What is the percent error?
You find that your measurement has a 17.1% error. You will use this calculation to compare your measurements to accepted values throughout your study of chemistry.
Density
The Discovery of Density
The discovery of density has roots that date back almost 2,000 years. The Greek scientist, engineer, and mathematician, Archimedes, discovered density in his bathtub. In this interactivity, read the story about the discovery of density by clicking on each of the vertical bars in order.
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Density Calculations Using Mass and Volume
In order to calculate density, you need to know how to calculate both mass and volume. View this presentation to learn more about density and the equation to calculate it. In addition, learn why the density of water causes it to behave differently from other liquids. Make sure to complete each of the practice activities in the interactivity.
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