Unit of matter density

What is a unit of density? Let us explain the features of a given physical quantity.

This term is an important indicator of oil, as well as various petroleum products.

Features of the term

In modern petrochemistry, such units of substance density as kg / m3, as well as g / m3, are used. With the help of such a value, calculations are performed, connected with the determination of the mass of the substance. In the presence of volume, as well as with a known density of matter, it is possible to determine the amount of petroleum products.

Determination of

The saturation of a mixture of a substance or a pure component is the amount of mass that is contained in one unit of volume. The unit of density in SI is kg / m3. For the value take the mass of one cubic meter of distilled water, which is taken at a temperature of four degrees.

Basically, not calculate its absolute value for the substance or mixture of components, but the relative density, which expresses the ratio of the mass of the mixture (component) to clean water of equal volume.

According to the numerical index, the values of relative and absolute density are the same, there are differences only in dimension. Relative does not have a unit of density.

In our country there is a special GOST 3900, according to which the density is determined at a temperature of +20 degrees Celsius.

For export oil and oil products, special international standards for density calculation are used. They imply the use of hydrometers and digital density analyzers.

In the United States and England, conditional magnitudes, such as degrees, are introduced, even special degrees Bome and IPA. Between them there is a connection, expressed by arithmetic equations.

In some reference materials, the density designation d204 is mentioned. In reality, this physical value is determined at different temperatures using the value of the coefficient of volumetric expansion.

Density as an independent indicator is important for petrochemicals. In addition, this physical term is used in determining the structural-group composition by analyzing a mixture of hydrocarbon fractions.

What determines the density

The units of density measurement indicate that this physical quantity is related to volume and mass. What other indicators can affect the value of density?

The density is affected by the chemical nature of the constituents, the fractional composition, the molecular weight of the constituents, the presence of dissolved substances, and the content of resinous substances. Depending on the depth and geological age, the density of the oil changes. In chemistry, use units of measurement of the density of matter, as g / cm3.

Methods for determining the density

In Russia, to determine the density, the areometric and pycnometric method is used. The second option is a long and time-consuming method, it gives a high accuracy of measurements. Its basis is the comparison of the mass of the calculated volume of the analyzed oil or oil product with the mass of water at equal temperatures. The result is a unit of density with an accuracy of 0.0001. Pycnometers are glass vessels with ground glass stopper. The volume of the vessels is allowed in 1, 5, 25 ml.

What is the specificity of the hydrometric method? There is an international standard by which the density of liquid petroleum products, pure oil can be determined in a laboratory way. The method involves the use of a glass hydrometer at +15 and +20 degrees Celsius.

The hydrometer is a cylindrical vessel, at the bottom of it there is a ballast. Its location must be necessarily symmetrical. Many hydrometers have a thermometer. A special scale is made on the device, the density unit is indicated. In order to increase the accuracy of the determinations, one can use a set of hydrometers, using several additional divisions on the scale.

This method determines the density of mobile transparent solutions, using the coincidence of the lower meniscus with the base of the hydrometer. When detecting the density of opaque liquids, read the hydrometer scale, choosing a coincidence with the upper meniscus bar.

With a smooth immersion of the hydrometer, after its establishment, the density parameters are calculated. In the event that there are differences from the temperature of +20 degrees, determine the density at the available temperature, then recalculate.

Calculations by density

In everyday life people often use comparative expressions: "light as air", "heavy as lead". In this case, almost none of them does not think about whether they have a certain meaning.

In the school physics course, the children are offered calculations in which three physical quantities are related: density, mass, volume. For example, it is proposed to calculate the mass of copper and steel bars having the same volume. To cope with this task, you need an indicator such as density. The denser the metal, the more mass the bar will have.

How to measure the masses of lead parts that have different weights? First, you need to determine the height, width, length of each of them, calculate the volume by the obtained parameters. Then you can use the lever scales, a set of loads. To determine the density, it is necessary to find the mass-to-volume ratio of the object.

Conclusion

What is density? This is a physical quantity that characterizes a certain substance. It is defined as the ratio of the mass of the substance to the volume. This parameter is denoted by the letter (po), the basic unit of measurement in the international SI system is kg / m3. It characterizes the substance itself, does not depend on the volume or mass of the initial sample. When the mass of the mixture or pure substance is tripled, the volume decreases exactly as much, while the density remains constant.