Effusion and Diffusion

QuickNotes

Effusion

• Not solely do gaseous particles move with high mechanical energy, however their tiny size allows them to maneuver through tiny openings as well; this method is thought as effusion. 
• For effusion to occur, the hole's diameter should be smaller than the molecules' mean free path (the average distance that a gas particle travels between serial collisions with alternative gas particles). 
• The gap of the outlet should be smaller than the mean free path as a result of otherwise, the gas may move and forth through the outlet.

• The above equation is Graham's Law, where:
• Rate 1 is the rate of effusion of the first gas (volume or number of moles per unit time).
• Rate 2 is the rate of effusion for the second gas.
• M1 is the molar mass of gas 1
• M2 is the molar mass of gas 2.

Example: 

What is the ratio of the rate of effusion of ammonia, NH3, to that of hydrogen chloride, HCl?

The NH3 effuses at a rate of 1.46 times that of the HCl.

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Diffusion

• According to Kinetic Molecular Theory, gasified particles area unit in a very constant state of motion, moving every which way speeds and in many various directions.
• Because of their kinetic energy at temperatures above absolute zero, all particles undergo diffusion.
• Diffusion refers to the method of particles moving from a locality of high concentration to at least one of low concentration.
• The speed of this movement could be a perform of temperature, consistence of the medium, and also the size (mass) of the particles. 
• Diffusion leads to the gradual mixture of materials, and eventually, it forms a whole mixture.

Particles moving from areas of high concentration to areas of low concentration.

The rate at which gases diffuse is inversely proportional to the square root of their densities.

Want an easy way to remember this? 
Small holes are effusion and big holes are diffusion!

To make sure you totally understand effusion and diffusion, check out this review video!

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Effusion and Diffusion Quiz