PPT Slide
- Effusion, is the process by which a gas escapes from its container through a tiny hole into an evacuated space.
- Grahamís law: the rate of effusion of a gas is inversely proportional to the square root of its molar mass.
- He gas effuses faster (at a higher rate) than the heavier oxygen gas (O2).
- Lighter gas effuses faster since the avg. speed of its molecules is higher; more molecules escape through the hole per unit time.
Notes:
When a beaker of water containing a thermometer is heated over a flame, the rapidly moving gas particles in the flame transfer kinetic energy to the atoms in the glass beaker, which vibrate faster and transfer kinetic energy to the molecules of water. The faster-moving water molecules collide more energetically with the atoms in the thermometer bulb, which in turn transfer kinetic energy to the atoms of mercury, causing the mercury to rise.