Help! Conversion between standard cubic volume of gas and mass

It is recommended to read a book on Principles of Chemical Engineering; the term “standard volume” refers to the volume under standard conditions. “\"Standard conditions\" refer to the temperature and pressure specified by the SI system. Flow rate can be divided into volumetric flow rate and mass flow rate, and conversions between them are necessary. This is like teaching someone how to fish; however, this book is a reference tool for those in this industry, and it can be understood without having a high level of education – it contains everything you need. Highly recommended.

This post was last edited by 2005011lcj on 2020-3-29 at 13:17. First, it is necessary to know that the density of hydrogen chloride gas is 9.346 kg/m3. The volume flow rate can then be calculated as 50/9.346 = 5.349 m3/h. Under these conditions, the compression factor Z is 0.9625; it can thus be considered an ideal gas to a certain extent. Since it is an ideal gas, the ideal gas law can be used directly. The calculated flow rate under standard conditions is 29.58 Nm3/h. Now let’s try another method. The direct calculation gives a gas density of 1.4992 kg/m3 under standard conditions. Therefore, the volumetric flow rate under standard conditions (298.15 K or 25°C and 101.325 kPa) is 50/1.4992 = 33.35 Nm3/h; it can be seen that there is still a slight difference. Because 0.9625 is actually a bit off from an ideal gas. It is recommended to use this result.

v = (m/M) * 22.4, with the unit being cubic meters; for hydrogen chloride, M = 36.5 and m = 50 kg, which gives the volume under standard conditions. This concept comes from high school chemistry; if one wants to calculate it for a pressure of 0.5 kilograms and a temperature of 20 degrees, the PVT equation can be used

Pressure 0.5 should be gauge pressure, while absolute pressure is used for calculations. The PR equation is part of chemical engineering thermodynamics.

Is PV=NRT the equation to use?