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Topic: Can diffusion occur in solids?  (Read 709 times)

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Offline Lioric

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Can diffusion occur in solids?
« on: January 27, 2019, 09:10:31 PM »
I see in most newer syllabus textbooks it says that diffusion is the mixing of fluids and diffusion cannot occur in solids
But when is search the web I see lectures and books written on the title diffusion in solids and when I studied I was taught that diffusion occurs in solids but at very very slow rate
So I was just wondering, in the newer findings, is diffusion considered non occuring in solids or is it so slow that they decided to say it doesn't happen?

This is the chemistry text book
Cambridge IGCSE® Chemistry Digital Edition Coursebook
Here is the link
https://www.ebooks.com/1756987/camb...edition-coursebook/harwood-richard-lodge-ian/
And here is the snapshot of the page which makes the claim


Offline Corribus

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Re: Can diffusion occur in solids?
« Reply #1 on: January 28, 2019, 10:25:32 AM »
I see in most newer syllabus textbooks it says that diffusion is the mixing of fluids and diffusion cannot occur in solids
This is about as wrong as wrong can be. Diffusion definitely occurs in solids.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

Offline Lioric

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Re: Can diffusion occur in solids?
« Reply #2 on: January 28, 2019, 11:55:30 PM »
Thank you
When recent text books say these things I just started to question my knowledge
No matter what syllabus, I believe that the fundamentals are the same

Offline Enthalpy

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Re: Can diffusion occur in solids?
« Reply #3 on: January 29, 2019, 10:45:10 AM »
Already centuries ago, alchemists knew that solid lead diffuses in solid gold.

Diffusion in solids serves in every production process for semiconductor chips. And to weld titanium aeroplane parts without melting. And to purify water by reverse osmosis. And so on and so forth.

So you found a book, possibly recent and of good reputation, that told you plain and utter nonsense? Welcome in the life of scientists. You realized that early, better for you.

In some cases, half of all books and courses are wrong. Like "Bose-Einstein condensation of electron pairs in BCS superconductor theory" despite BCS excludes explicitly a B-E condensation.

In extreme cases, nearly 100% of all books and courses are wrong despite checking would be so easy. Like "the timbre of a musical sound results from its harmonic spectrum". Or "BCC and hexagonal metals are fragile while FCC are ductile".

Moral:
  • Reputation is not trustworthy. Peer review neither.
  • Consensus is not a proof.
  • Scientists don't behave scientifically.
  • Science isn't an other religion where the professor would be a better priest.
  • You decide what you believe.

Offline Corribus

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Re: Can diffusion occur in solids?
« Reply #4 on: January 29, 2019, 03:15:39 PM »
We don't have all the context, because we're only seeing one page. Nevertheless, it seems like this isn't just oversimplification because "never occurs" is not a really good simplification of "usually occurs much more slowly in solids compared to liquids". It is noteworthy that this is not the only error (or simplification, if you prefer) in the image. For example, diffusion does not always lead to uniform concentration everywhere, even at quasi-infinite time ("their particles are evenly spread - their concentration is the same throughout"). E.g., a substance dissolved in one medium diffusing into another medium, will not have an equivalent concentration across both media, because of different solubilities in each medium.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

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