Kaasupycnometria

Kaasupycnometria is a Finnish term that translates to "gas pycnometry" in English. It refers to a laboratory technique used to determine the density or specific gravity of a solid material by measuring the volume it occupies using a gas as the displacement fluid. This method is particularly useful for powdered or porous materials that might absorb a liquid pycnometer fluid, leading to inaccurate results.

The principle behind kaasupycnometria is based on Boyle's Law, which states that for a fixed amount of gas at a constant temperature, the pressure and volume are inversely proportional. In a typical gas pycnometer, the sample of unknown volume is placed in a sample chamber. This chamber is then connected to a reference volume filled with a known gas, typically helium, at a known pressure. By allowing the gas to expand from the reference volume into the sample chamber (or vice versa), the change in pressure is measured. Using the known volume of the reference chamber and the measured pressure changes, the volume of the solid sample can be calculated.

Once the volume of the sample is determined, its density can be easily calculated if its mass is known. Kaasupycnometria is widely used in materials science, chemistry, and pharmaceuticals for characterizing the physical properties of various substances, including powders, catalysts, and porous ceramics. The accuracy of the measurement depends on factors such as the purity of the gas used, the temperature control, and the proper sealing of the system to prevent gas leakage.