DENSITY is a physical property of pure substances and, as such, does not vary from sample to sample.  Because the density of a pure substance remains constant, no matter how much of the substance is present, its value can be used to identify the substance.

Geometric measurements can be used to calculate the volume for regular shaped solids.  However, water displacement measurements must be used to calculate the volume of irregularly shaped solids.  Part of this experiment will involve the calculation of density for an unknown solid using both GEOMETRIC and DISPLACEMENT calculations for its volume.

Water is a relatively dense liquid and most other liquids are less dense than water.  As a result, most liquids float on top of water.  Solids are generally more dense than water and, thus, sink to the bottom of a container filled with water.  Part of this lab will involve the determination of relative density values for some liquids and solids.

Since density is calculated from mass and volume measurements, it is important to record all measured values to the proper number of significant digits.  The number of significant digits is determined by the type of equipment used to take the measurement.  Simple rules are used to determine the number of significant digits in answers to calculations involving measured data.  A portion of this lab will involve a comparison of significant digits for volume measurements using different volume measuring devices.