Osmium's density is just a hair greater than that of indium.This ultrafine form of SiO 2 is found in everything from toothpaste to coffee creamer.No surprise that the lightest element forms the lowest density solid of any pure substance.The density at the Sun's center is estimated to be about 160 g/cm 3. But bear in mind that it is all very hot gas. The Sun's very low average density may surprise you.Besides its extremely low density, many aerogels exhibit remarkably low thermal conductivity. Remove the water from a colloidal gel, and you get an aerogel, sometimes called "solid smoke".The world's lowest-density class of solids, invented in 2011.Thus if we find that a given volume of a substance at 20° C weighs 1.11 times as much as the same volume of water measured at 4☌, we would express its specific gravity asĪlthough most chemists find density to be more convenient to work with and consider specific gravity to be rather old-fashioned, the latter quantity is widely used in many industrial and technical fields ranging from winemaking to urinalysis. In making actual comparisons, however, the temperatures of both the material being measured and of the equivalent volume of water are frequently different, so in order to specify a specific gravity value unambiguously, it is necessary to state the temperatures of both the substance in question and of the water. At 4☌, water has its maximum density of almost exactly 1.000 g mL –1, so if the equivalent volume of water is assumed to be at this temperature, then the density and specific gravity can be considered numerically identical. The presence of "volume" in this definition introduces a slight complication: volumes are temperature-dependent owing to thermal expansion. However, one can also construct other densities like a "charge density" for example.ĭensity can be expressed in any combination of mass and volume units the most commonly seen units are grams per mL (g mL –1, g cm –3), or kilograms per liter. What we conventionally call the "density" is more precisely known as the "mass density". The general meaning of density is the amount of anything per unit volume. The volume units milliliter (mL) and cubic centimeter (cm 3) are identical and are commonly used interchangeably. This quantity \(\rho\) is known as the density, which is usually defined as the mass per unit volume: Denoting mass and volume by \(m\) and \(V\) respectively, we can write the equation of each line as \(m = \rho V\), where the slope \(\rho\) (Greek lower-case rho) is the proportionality constant that relates mass to volume. The only difference between these plots is their slopes. the plots are all straight lines, which signify direct proportionality.the plots all have the same origin of (0,0): if the mass is zero, so is the volume.These plots show how the masses of three liquids vary with their volumes. It is this ratio, (mass ÷ volume), that we are concerned with in this Module. T he ratio of two extensive properties is always an intensive property - one that characterizes a particular kind of matter, independently of its size or mass. Mass and volume are measures of the quantity of a substance, and as such are defined as extensive properties of matter. But in making such statements, we are implicitly comparing equal volumes of these substances: after all, we know that a cup of sugar will weigh more than a single ordinary steel nail. Most of us have long understood that "oil is lighter than water", or that iron is "heavier" than sugar.
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