Molecular Effusion and Diffusion

Molecular Effusion and Diffusion - • Latex is a porous...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Molecular Effusion and Diffusion Kinetic-molecular theory stated that The average kinetic energy of molecules is proportional to absolute temperature Thus, at a given temperature, to different gases (e.g. He vs. Xe) will have the same average kinetic energy The lighter gas has a much lower mass, but the same kinetic energy, therefore its rms velocity (u) must be higher than that of the heavier gas where M is the molar mass Example Calculate the rms speed, u , of an N 2 molecule at room temperature (25°C) T = (25+273)°K = 298°K M = 28 g/mol = 0.028 kg/mol R = 8.314 J/mol °K = 8.314 kg m 2 /s 2 mol °K Note: this is equal to 1,150 miles/hour! Effusion The rate of escape of a gas through a tiny pore or pinhole in its container.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: • Latex is a porous material (tiny pores), from which balloons are made • Helium balloons seem to deflate faster than those we fill with air (blow up by mouth) The effusion rate, r , has been found to be inversely proportional to the square root of its molar mass: and a lighter gas will effuse more rapidly than a heavy gas: Basis of effusion • The only way for a gas to effuse, is for a molecule to collide with the pore or pinhole (and escape) • The number of such collisions will increase as the speed of the molecules increases Diffusion: the spread of one substance through space, or though a second substance (such as the atmosphere)...
View Full Document

This note was uploaded on 11/22/2011 for the course CHEMISTRY CHM1025 taught by Professor Laurachoudry during the Fall '10 term at Broward College.

Page1 / 2

Molecular Effusion and Diffusion - • Latex is a porous...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online