A Simple Question about Diffusion and ion speed

In summary, Mark is seeking information about a process involving an ion mobility with a diffusion coefficient of 9.3 x 10-5 cm2/s. He is curious about how long it would take for the ion to travel 10 cm and asks if there is a way to calculate the ion's speed based on D. Mapes responds that the general approximation for diffusion time is t=L^2/D, which in this case would be approximately 12 days. Mark thanks Mapes for the helpful information.
  • #1
WarpedWatch
38
0
Greetings,
I'm trying to get an intuitive understanding about a process involving an ion mobility that (I'm told) has D = 9.3 x 10-5 cm2/s. I'm assuming that D is a diffusion coefficient.

I'd like to know approximately how long it takes for the ion to travel about 10 cm. Would this be something that happens in a matter of femtoseconds, minutes, hours, weeks, years... or what? Unfortunately I don't have any more information than that, so is there some way to calculate (or just roughly guess) the ion speed based on D?

many thanks,
Mark
 
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  • #2
The general approximation for diffusion time is [itex]t=L^2/D[/itex]. The exact answer depends upon the boundary conditions, but this estimate is good to within an order of magnitude. In your case: about 12 days.
 
  • #3
Mapes,

That's great! Thanks very much for your help on this!
:smile:

Mark
 

1. What is diffusion?

Diffusion is the process by which particles move from an area of higher concentration to an area of lower concentration. This movement occurs due to random molecular motion and does not require energy.

2. How does diffusion happen?

Diffusion occurs due to the random motion of particles. As particles move, they collide with each other and spread out, causing the concentration to become more uniform.

3. What factors affect the rate of diffusion?

The rate of diffusion is affected by several factors, including temperature, concentration gradient, and molecular weight. Higher temperatures, steeper concentration gradients, and smaller molecular weights all lead to faster diffusion rates.

4. What is ion speed?

Ion speed refers to the speed at which ions move through a medium. This speed is influenced by factors such as the charge and size of the ion, as well as the properties of the medium the ion is traveling through.

5. How is ion speed related to diffusion?

Ion speed is directly related to diffusion, as ions are one type of particle that can undergo diffusion. The speed at which ions move will affect the rate of diffusion and the overall movement of particles in a system.

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