Animation showing two gases at different pressures equalising their pressure when contact is made. The dials at the sides show the pressures P of each chamber. Initially, the chamber at left contains far more molecules of gas, which collide more frequently with the walls of the chamber, leading to a higher pressure. The chamber at right has fewer molecules and therefore fewer collisions. When the barrier is lifted, the molecules can travel into the adjacent chamber. More molecules from the high_pressure chamber move to the low_pressure side than vice versa, eventually leading to the pressure equalising. This animation is part of a series on the ideal gas laws. See K003 3525_3530 for the complete set.