Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Petrochemicals on 11/09/2023 21:48:44

Title: Why isn't my salt water evaporating?
Post by: Petrochemicals on 11/09/2023 21:48:44

I have some liquid which I am assuming to be water as it is not oily, has no scent, has the same viscosity and have ruled out anything else. It is only a few drops but it is on some salt from a bag of salt and grit that is used for pavements in the winter. As I said, it is only a few small drops  but it doesn't seem to wish to evaporate, it has been there for at least 12 hours in a hot environment.

Title: Re: Why isn't my salt water evaporating?
Post by: paul cotter on 14/09/2023 21:18:56

Hi Petro, I typed out a detailed response to your query and when I tried to post it came back as an error but it gave me the option of reposting-- I tried this to be accused of double posting, AAGH!!. I'm tired, have been travelling and i'm not doing this again, tonight. If no other answers arrive tomorrow I'll try again. 

Title: Re: Why isn't my salt water evaporating?
Post by: Bored chemist on 15/09/2023 08:54:22

Could there be calcium or magnesium  chloride in there?

Title: Re: Why isn't my salt water evaporating?
Post by: evan_au on 15/09/2023 09:09:02

May be hygroscopic salts in there - they absorb moisture from the atmosphere (which BC was alluding to).
https://en.wikipedia.org/wiki/Hygroscopy

In extreme cases, this becomes "deliquescence" - these compounds absorb water from the atmosphere, and dissolve in the extracted water.
https://en.wikipedia.org/wiki/Hygroscopy#Deliquescence

Title: Re: Why isn't my salt water evaporating?
Post by: paul cotter on 15/09/2023 20:13:10

Thanks, Evan_au. As I explained above I answered similarly in a more verbose but most likely less clear answer that evaporated.

Title: Re: Why isn't my salt water evaporating?
Post by: Petrochemicals on 15/09/2023 21:57:10

It has evaporated finally

Quote from: Bored chemist on 15/09/2023 08:54:22

Could there be calcium or magnesium  chloride in there?

I do not know, it's rock salt, mined probably so there may be anything in it, plus any additives.

Quote from: evan_au on 15/09/2023 09:09:02

May be hygroscopic salts in there - they absorb moisture from the atmosphere (which BC was alluding to).
https://en.wikipedia.org/wiki/Hygroscopy

In extreme cases, this becomes "deliquescence" - these compounds absorb water from the atmosphere, and dissolve in the extracted water.
https://en.wikipedia.org/wiki/Hygroscopy#Deliquescence

Mmm, it may be something like this, I believe it may have been liquid water but it persisted.

Quote from: paul cotter on 15/09/2023 20:13:10

Thanks, Evan_au. As I explained above I answered similarly in a more verbose but most likely less clear answer that evaporated.

Thanks for trying.