#Density definition chemistry free
Note that the following values are given at standard temperature and pressure (STP) conditions. Since gases are free to expand and contract, the densities of the gases vary considerably with temperature, whereas the densities of liquids vary little with. Listed below are the densities for common elements and materials. For example, water increases in density between its melting point at 0☌ and 4☌. There are, however, a few notable exceptions. The density of an object represents its compactness, or mass per given volume of a substance, and is most commonly represented as grams per milliliters. Increasing the temperature of a substance almost always decreases its density due to expansion and increasing volumes. The inverse is true for the density of materials subjected to changing temperature. As the same mass is contained in a smaller volume, based on ρ = M/V, its density will increase. If you were to squeeze the ball in your hand, its weight remains the same however, its volume changes as it is being compressed. For example, a sponge ball starts with a particular density. Increasing the pressure on an object or substance almost always increases its density. As such, densities for various materials and elements are usually measured and recorded at standard conditions for temperature and pressure (STP), i.e., 273.15°K (0.0☌) and 100 kPa (0.987 atm).
Therefore, if the relative density of an object is less than one, that means that it is less dense than water and will likely float.Īs mentioned previously, density varies depending on environmental temperature and pressure. These dimensionless parameters represent the ratio of the mass density of a material to that of a standard material, typically water. To simplify the comparison of densities of different materials across different units of measurement, other terms such as relative density or specific gravity are used. Mass density is known by several different terms, including density, volumetric mass density and specific mass. This expansion and reduced density can lead to several defects, such as cracking and spalling in concrete. As iron corrodes, the metal oxidizes to form rust, which occupies more space than the original metal. Mass density can also be related to an object's level of corrosion. Based on the formula above, if the volume of the gas expands, its density decreases. In other words, their volume increases with increasing temperature. However, this measurement is not necessarily constant mass density depends on several factors, including temperature and pressure.įor example, gases expand when they are heated. Mass density is a representation of the amount of mass (or the number of particles) of a substance, material or object in relation to the space it occupies. Mathematically, mass density is expressed using the following formula: Mass density is represented by the lower-case Greek letter rho, ρ, although the Latin letter 'D' has also historically been used.
This parameter can be expressed using several different units, including kilograms per meter cubed (kg/m 3) and pounds per square foot (lb/ft 2). The mass density of an object is defined as its mass per unit volume.
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