specific volume

Specific volume is a property of materials, defined as the number of cubic meters occupied by one kilogram of a particular substance. The standard unit is the meter cubed per kilogram (m ³ /kg or m ³ · kg ^-1 ).

Sometimes specific volume is expressed in terms of the number of cubic centimeters occupied by one gram of a substance. In this case, the unit is the centimeter cubed per gram (cm ³ /g or cm ³ · g ^-1 ). To convert m ³ /kg to cm ³ /g, multiply by 1000; conversely, multiply by 0.001.

Specific volume is inversely proportional to density . If the density of a substance doubles, its specific volume, as expressed in the same base units, is cut in half. If the density drops to 1/10 its former value, the specific volume, as expressed in the same base units, increases by a factor of 10.

Imagine a variable-volume, airtight chamber containing a certain number of atoms of oxygen gas. Consider the following four examples:

• If the chamber is made smaller without allowing gas in or out, the density increases and the specific volume decreases
• If the chamber expands without letting gas in or out, the density decreases and the specific volume increases
• If the size of the chamber remains constant and new atoms of gas are injected, the density increases and the specific volume decreases
• If the size of the chamber remains constant and some atoms are removed, the density decreases and the specific volume increases

Also see density , kilogram , meter cubed , volume , and SI (International System of Units).