Questions tagged [diffusion]

For questions referring to the process by which molecules move as a result of their kinetic energy.

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15
votes
1answer
281 views

Is there a consensus on whether amber can seal in air bubbles for millions of years?

I read about deriving the oxygen content in the atmosphere in the Cretaceous by analyzing the air trapped in bubbles in amber from that period, but I have also found papers disputing the study's ...
4
votes
0answers
135 views

Reaction-diffusion equation using Lattice-Boltzmann method

I'm struggling to get a working LBM reaction-diffusion implementation. I have a pretty weak mathematics and physics background, and thus I'm having a hard time understanding the notations around the ...
1
vote
0answers
266 views

How to write mass balance equation for the scenario when molecules are getting generated inside an sphere?

I am working on the physical understanding of diffusion through a nano machine(a shell with hollow interior in which molecules are produced) and have taken few assumptions: There is rate $r_T$ with ...
3
votes
1answer
224 views

Are there any solids that undergo diffusion?

Are there any solids that undergo diffusion? Introduction: In school, my teacher is only talking about diffusion happening in liquids and I though that it may be able to happen to solids also. ...
3
votes
1answer
110 views

What kind of unit is this [A*m^2/mol]?

I found a term on this website that gives a unit of [A*m^2/mol]. The equation is: $k_d^{eff}=\frac{2RT\kappa^{eff}}{F}(t^+-1)\left(1+\frac{\text{d}\ln(f)}{\text{d}\ln(c)}\right)$ where R is the gas ...
3
votes
2answers
436 views

Is pressure equalization “diffusion”?

There is another question on the site which is: Two containers, A and B, connected by a closed valve were evacuated and the Chlorine gas (Cl2) with a pressure of 200kPa was put into A and Oxygen (...
-2
votes
1answer
464 views

Why do universal indicators in titration have to be swirled?

Why do universal indicators in titration have to be swirled? Here's a specific example: I am using methyl orange along with hydrochloric acid to test the alkalinity of a set of household cleaners (...
7
votes
3answers
2k views

When is diffusion steady-state?

Fick’s first law of diffusion can be used when $\mathrm{d}C/\mathrm{d}t=0$. If the concentration gradient is time-variant, then we must use Fick’s second law. However, when is diffusion steady-state ...

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