physique chimie college lycee






Description: Interactive simulation to show the behavior of the gaseous molecules when the volume increase or decrease. Atmospheric pressure. What is the relation between pressure and number of shocks of the molecules on the wall of a container?


A gas is elastic!

It regains its shape (that of the container), ie it returns to the equilibrium position when the stress exerted on the container ceases. The animation shows the agitation of the molecules of oxygen and nitrogen in the air, inside and outside a syringe. The pressure variation and interpretation by this model are visible when the syringe plunger is actuated.


P1.V1 = P2.V2


The pressure is interpreted by the number of impacts between molecules and molecules on the walls of the receptacle.


1.air can neither enter nor exit the syringe

2. it is considered that the piston can slide without friction

3. the air present around the device is not modeled except the parts which oppose the action of the internal air on the piston, visible by activating the button "show ambient air".



Boyle's law: Boyle's law, also referred to as the Mariotte's law (in France), describes how the pressure of a gas tends to increase as the volume of the container decreases.

In other words:

The absolute pressure exerted by a given mass of an ideal gas is inversely proportional to the volume it occupies if the temperature and amount of gas remain unchanged within a closed system.


flash animation        .exe (Windows)        .app (Mac)        video




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