Relative density gas - a comparison of the relative molecular or molar mass of the gas with the same measure of another gas.As a rule, it is defined with respect to the lightest gas - hydrogen.Also frequently gases compared with air.
To show what gas is selected for comparison, before the symbol of the relative density of the added index and the name written in parentheses.For example, DH2 (SO2).This means that the density of sulfur dioxide was calculated from the hydrogen.Read it as "the density of sulfur dioxide to hydrogen."
To calculate the density of the gas to hydrogen, you need to use the periodic table to determine the molar mass of the test gas and hydrogen.If this chlorine and hydrogen, the indicators will look like: M (Cl2) = 71 g / mol and M (H2) = 2 g / mol.If the density divided by the density of hydrogen chloride (71: 2) to yield 35.5.That is chloro 35.5 times heavier than hydrogen.
relative density of the gas from the external environment does not depend.This is due to universal law of gases, which are reduced to the fact that the change in temperature and pressure does not alter their volume.Any changes to these parameters measurements are made the same way.
To determine the density of the gas needed by experiment flask, where it can be put.The flask with the gas must be weighed twice: the first time - it pumped out from the air;second - filling it with the gas.It is also necessary to measure the amount of advance of the flask.
First you need to calculate the difference between the masses and divide it by the value of the volume of the flask.The result is a density of gas at the specified conditions.Using the equation of state is possible to calculate the required rate under normal or ideal conditions.
Learn density of certain gases can be on the summary table, which has a ready-made information.If the gas is brought to the table, then this information can be taken without the use of additional calculations and formulas.For example, the density of water vapor can be found on the table of the properties of water (Directory Rivkin SL et al.), Its electronic counterparts or with a program like WaterSteamPro and others.
However, various liquid equilibrium with the vapor occurs at different densities of the latter.This is due to the difference in the forces of intermolecular interaction.The higher it is, the faster it will reach equilibrium (e.g., mercury).In volatile fluids (eg, air) equilibrium may occur only if a large vapor density.
density different natural gases varies from 0.72 to 2.00 kg / m3 or higher, relative - from 0.6 to 1.5 and above.The highest density of gases with the highest content of heavy hydrocarbons H2S, CO2 and N2, the lowest - from the dry methane.
natural gas properties are determined by its composition, temperature, pressure and density.The latter figure is determined by laboratory methods.It depends on all the above.It is possible to determine the density of different methods.The most accurate - accurate weighing on the scales in thin-walled glass bulb.
air density more than the same index of natural gas.In practice this is taken as the ratio of 0.6: 1.Static air pressure decreases faster as compared with the gas.At a pressure of 100 MPa, the density of natural gas may exceed 0.35 g / cm3.
An increase in the density of natural gas may be accompanied by an increase in temperature of hydrate.Natural gas is a low density form hydrates at a higher temperature than gases with higher density.
The gas industry density meters are just beginning to be used, and there are still many issues that are related to the peculiarities of their use and inspection.
