Pressure in gasses and liquids is one of the curricular content areas in chemistry and physics lessons at “Sekundarstufe I”(secondary level). In this module, we want to support students in setting up, conducting and observing an experiment to explore the connection between force, surface area and resulting gas pressure. Thereby we want to create a laboratory-like introduction to the basic concept of pressure, supported by digital data acquisition.
To determine the connection between force, surface area and pressure, the following materials are used in this module:
- Three syringes with different piston areas or volumes
- Three different mass pieces
- Digital gas pressure sensor
- Digital terminal
- Mount material
Teaching impulses for data acquisition, processing and evaluation with the videos
The learners work individually or in small groups with the videos. Beforehand, it should be discussed which data from the video is to be collected (e.g., piston diameter of the syringe, which mass piece is used, pressure inside the unloaded syringe, pressure inside the syringe, loaded with the mass piece). When working in small groups, it is advisable to use the video versions 02, 03 and 04. Afterwards, the different results can be compiled and compared in class.
The instrumental and analytical skills of the learners are trained through data preparation and evaluation. In order to determine the connection between force, surface area and pressure, the students have firstly to calculate the corresponding surface area from the diameter of the syringe plunger and also the weight force of the mass pieces.
By plotting the measured values in a force-pressure diagram, students should recognise the linear relationship between the two variables. The point of intersection of the compensation line with the y-axis corresponds approximately to the pressure inside the unloaded syringe, the slope approximately to the reciprocal value of the piston area 1/A.
Tip: For this module, an interactive learning video is available.
Further information can also be found in Meier, M., Stinken-Rösner, L. & Zeller, D. (2022): Vom Rezipieren zum Interagieren – Interaktive Videoformate für den naturwissenschaftlichen Unterricht. Unterricht Biologie 475, 44–47.
The (differentiated) video material “Pressure in gasses”:
Video version 01
Experiment (Complete)
In the video, the gas pressure inside three syringes with different piston surfaces is varied by placing different mass pieces on the respective piston. The experiment is carried out three times in succession.
Video version 02
Experiment
(Individual measurement series)
Three measurement clips of the experiment are available. Each contains a series of measurements.
Video version 03 Experiment (Injection)
Three measuring clips are available. In each one, one of the syringes is weighted with three different mass pieces, one after another. Three successive runs of the measurement are performed.
Video version 04
Experiment (Masses)
Three measurement clips are available. In each clip, all three syringes are weighted with the same mass piece, one after another. Three successive runs of the measurement are performed..
Here you can download a picture with all the necessary materials. It can serve as a support for your pupils and as a first impulse for planning the experiment.