Density describes the relationship between the mass of a substance and its volume. It is given by the formula density equals mass divided by volume (density = mass/volume). Therefore, if the density and mass of a substance are known, the volume may be determined by dividing the mass by the density (volume = mass/density).
Mass may also be determined by restructuring the formula so that volume multiplied by density equals mass (mass = volume x density). In determining the mass or volume of a substance from its density, the density of the substance must be known.
Identify the density of the substance being used. Density is a physical property of a substance. These values can be determined in reference materials for the substance. For example, pure water has a density of one gram per cubic centimeter at four degrees Celsius. Note that the density of a substance changes with temperature.
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Measure the mass of the substance. This may be done with a triple-beam balance or electronic balance. Be sure to zero the balance before any measurement is made.
Zeroing an electronic balance simply involves pressing the tare button while the pan is empty. Zeroing a triple-beam balance requires the movable masses to be slid to the zero position and aligning the pointer with the level mark. If the pointer is not aligned, rotate the tare adjust knob, usually located under the pan, until the pointer is level.
Divide the mass by the density of the substance to determine the volume (mass/density = volume). Remember to keep the units of measure consistent. For example, if the density is given in grams per cubic centimeter, then measure the mass in grams and give the volume in cubic centimeters.