you need
  • - paper;
  • - Calculator;
  • - handle;
  • - gas pressure (from the problem or in a table);
  • - the temperature at which you want to determine the density of
  • - periodic table.
Record on paper Mendeleev-Clapeyron equation for ideal gases: PV = (m / M) RT.It can be used for saturated steam, but as soon as the gas density is comparable to the density of the saturated vapor, the equation can not be used in the calculation - it will show an incorrect result.Another gas laws are not subject to saturated steam.
equation is derived from the recorded density of saturated steam.It is equal to mass divided by volume.Therefore, the equation is transformed: P = (p us. Steam / M) RT.From here you can write the formula for finding the density of saturated steam: p = PM / RT.Where P - is the gas pressure.His table value is usually given in the problem, depending on the temperature.If not given, find the table for your temperature.R - is the universal gas constant, equal to 8.31 J / (K * mol).
If you know the temperature in degrees Celsius, then it is in degrees Kelvin (denoted R).To do this, add 273 to the known temperature as -273 - is an absolute zero on the Kelvin scale.
Find the molar mass of the liquid M. It can be calculated by means of the periodic table.The molar mass of a substance is numerically equal to the molecular.Locate in the table of atomic masses of all elements contained in the material, and multiply by the number of corresponding atoms in the molecule.The sum of these values ​​gives the molecular weight of the substance.
Substitute the last expression is known values.Pressure P necessary to substitute in Pa.If the conditions given in kPa, then multiply it by 1000. The molar mass by substituting translate in kg / mole (divide by 1000), as in the periodic table it is given in g / mol.Use the calculator will calculate the density of the saturated vapor.Results obtained in kg / m3.