Wednesday, August 17, 2011

Measurement, Part 1: Introduction


All science is based on analyzing data. There are two types of data in chemistry. Qualitative data is based on descriptions such as color, state and luster. Quantitative data is based on numerical measurements.
Chemistry represents its quantitative data using the metric system.  Mass is measured in grams, volume in liters, length in meters, and temperature in Celsius or the Kelvin scale. EVERY QUANTITATIVE MEASUREMENT MUST HAVE BOTH A QUANTITY AND A UNIT.
Numbers mean nothing without a unit!
Volume is the amount of space occupied by a substance.  It can be measured in a derived unit such as liters or gallons, or as a unit of distance^3 such as cm^3 or ft^3.
Mass is the amount of matter present in a substance and is measured in grams.  Weight and mass are not the same thing.  Weight is the pull of gravity on an amount of matter and is dependent on location.  The same object will weigh less on the moon than on Earth, but its mass does not change.

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