Effusion is the movement of gas molecules from an enclosed container through a small hole into a vacuum.

The following animation will show an illustrion of the effusion of a gas, at the molecular level .

Explore how the moelcular weight of a gas influences the rate of effusion. Choose hydrogen gas first. Count the number of molecules of hydrogen that escape in 30 sec.

Predict the rate of effusion for for oxygen gas. Then do the simulation and compare your calculated value to the experimental value.

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