Density (d) is the mass per unit volume of a body (matter); d = m/σ g/cm3, where m is
mass and a s - volume body.
Relative density is called attitude P. this body to P. the other. For solid and liquid objects this value is determined with respect to P. distilled water, for gas - against P. hydrogen (P. hydrogen), oxygen (P. oxygen) and air (the density of the air). Normal gas density is the mass of 1 liter of gas at 0 degrees Celsius and pressure 1 ATM. With increasing pressure P. increases with increasing temperature in most cases, reduced.
Density measurement is necessary to identify many physico-chemical variables, such as the molecular weight, molecular refraction, concentration and other change P. you can judge for chemical processes. In sanitary-hygienic, clinical and biochemical laboratories use the following methods of measurement P. liquid and solid bodies: a) based mass of liquid and solid bodies found by a series of weighings filled by the relevant substance pycnometer (glass flask of the specified capacity); b) hydrostatic - mass and volume of the substance is determined by hydrostatic weighing scales Westphal; C) flotation - body density is determined by P. fluid in which this body in case of equality of densities is in a state of neutral equilibrium, that is, not drowning and nothing POPs up. Often define P. using density (see).