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This java applet shows a microscopic model for an ideal gas. The pressure that a gas exerts on the walls of its container is a consequence of the collisions of the gas molecules with the walls.

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In this model:

1.The molecules obey  of motion.

2.The molecules move in all direction with equal probability.

3.There is no interactions between molecules

4.The molecules undergo elastic collisions with the walls.

5.The gas particles are assumed to have zero


You can change the following parameters

  1. N: Total number of molecules

  2. P: The pressure of the system

  3. v: The velocity of each molecules.

  4. The width of the container (Click near the boundary and Drag the mouse)


The volume of the container is adjusted automatically according to the above parameters.

Starting numbers are 200,50,100 since the reset button works strangely.

The animation is suspended when you press the mouse button. It is resumed when you release the button.


1) What happens to the volume when the number of molecules is doubled?  The volume doubles halves


2) What happens to the volume when the number of molecules is tripled?  The volume


3) What is the relationship between number of molecules and volume? directly proportional  indirectly proportional


4)  If the pressure of the system is doubled what is the effect on the volume?  


5) If the pressure of the system is quadrupled what is the effect on the volume?


This shows and inversely proportional relationship between pressure and volume.


6) Tick all of the following that would increase atomic velocity in this model.

heat    catalyst    bigger box


7)  The ideal gas law works best on real gases with (tick all that apply)

low T    high T    low pressure    high pressure


8) Helium is probably the closest real gas to ideal because


The ideal gas equation is:


P = pressure in Pa (where 1atm = 1.013x105 Pa),

T= temperature in Kelvin,

V=volume in m3,

n=number of moles

R = gas constant8.314 J/K mol


9) What is the pressure, in Pa, of 3 moles of gas at temperature 100K which has a volume of 0.2m3 ?  Pa


10) What is the temperature of 5 moles of gas at 2 atm pressure with a volume of 2m K


11) How many moles of an ideal gas are present at 500oC in a 1000cm3 container with pressure 0.1 atm? mol