According to Graham's law, the following applies to the outflow of gases:
The following applies to the outflow times:
So if one knows the outflow times of two gases and the molar mass of one gas, then the molar mass of the other gas can be calculated according to
As a modification to the original Bunsen effusiometer, in the training area to illustrate the relationships, the determination can be made with the aid of a vertically attached piston sampler . The piston syringe has a stopcock at the bottom and a glass tube which is closed with a nozzle. The gas syringe is first filled with a known gas and the time it takes for it to flow out is determined. One proceeds accordingly with the unknown gas.
- For 100 ml of an unknown hydrocarbon compound, the outflow time t 2 = 9.0 seconds and for 100 ml nitrogen t 1 = 8.8 seconds. The molar mass for nitrogen is M 1 = 28 g / mol.
- It could be ethane .
- R. Brdička: Fundamentals of physical chemistry, VEB Deutscher Verlag der Wissenschaften Berlin 1967, p. 207
- Böse / Schmidt: Quantitative experiments with the piston sampler, Diesterweg Salle Frankfurt 1972, p. 26, ISBN 3-425-05076-1