Just trying to get an idea of exactly how long it takes before it's unusable. Have checked the stability threads but there doesn't seem to be any real answer for certain.
Endofpain
Student
- Dec 21, 2024
- 127
SN won't react with oxygen at room temp to any signuficant degree while in crystalline form and not dissolved.
I don't know where the myth comes from that SN will get oxidized to NO3- just by leaving it out in air for limited time.
I don't know where the myth comes from that SN will get oxidized to NO3- just by leaving it out in air for limited time.
Oh wow, interesting. Is there any chance you have a source for this? No offence, not arguing (I don't know any better anyway), but it just goes against everything I have read so far.
As a person who works with chemicals, rule of thumb is just to keep them in their original containers, closed as much as possible, in a cool place away from sunlight. If you think about labs that open/close these containers a lot, the chemicals inside probably exposed to air for a total time of a day, if not more. Also, unsealed chemicals can sit on shelves for decades and be fine (we have some bottles that are older than I am).
It is important to keep it away from moisture, so if you are in a particularly humid area, that is not good. Just keep it closed until you are ready to test/use and you should be fine.
It is important to keep it away from moisture, so if you are in a particularly humid area, that is not good. Just keep it closed until you are ready to test/use and you should be fine.
A day? Yeah, you're probably fine.
This is almost a century old so perhaps there have been further investigations since, but at standard conditions you'll see very little oxidation:
www.nature.com
A very brief bit of research suggests oxidation is most "efficient" at 65 degrees Celsius, but that's different to happening most quickly, which is at very high temperatures.
I think generally people like to take an abundance of caution, especially when making guides. I might be wrong, but I think there are cases of attempts failing where it has been speculated that the cause is contamination of the product - that's the impression I've got from people's general concerns about degradation.
To be frank, contamination with sodium chloride or, say, an acid like lemon juice is going to be a bigger concern.
This is almost a century old so perhaps there have been further investigations since, but at standard conditions you'll see very little oxidation:
Photo-Oxidation of Nitrite to Nitrate - Nature
THERE is considerable difference of opinion regarding the possibility of the oxidation of nitrites by oxygen to nitrates. Berzelius reported that when aqueous solutions of alkali nitrites are boiled in air, they absorb oxygen with the formation of nitrates. G. Lunge and E. Frémy, J. Lang1 and...
www.nature.com
A very brief bit of research suggests oxidation is most "efficient" at 65 degrees Celsius, but that's different to happening most quickly, which is at very high temperatures.
I think generally people like to take an abundance of caution, especially when making guides. I might be wrong, but I think there are cases of attempts failing where it has been speculated that the cause is contamination of the product - that's the impression I've got from people's general concerns about degradation.
To be frank, contamination with sodium chloride or, say, an acid like lemon juice is going to be a bigger concern.
Endofpain
Student
- Dec 21, 2024
- 127
Sure. Don't trust anybody on the internet :)
Keep in mind that solutions of NO2- were tested.
Don't trust anybody on the internet indeed. Yes, sn in it's crystal form does react and change if left in open air but it's a slow process. 3 months in open air was reduced to half it's purity if i remember correctly. Just keep it closed like it's recommend, why must you leave it open for days anyways?
The reason I ask is because I transferred some into a small container which I thought was airtight at the time in order to use later that day, before realising I wasn't ready. I realised it probably wasn't as airtight as I thought it was when I got back home a day later. After that I put it in a bag which also may not have been completely airtight. Just wondering if I would still be able to use that or if it's better to use what I have in its original container still.
I saw a thread (cant find again, sorry!) that had a table for the longevity of SN. It stated the following:
Stored airtight: few years
In air: few weeks
Dissolved in water: few hours
It also stated that momentary air exposure is fine, ie after a day putting it back in an airtight container will put it back in "few years" category
Make of that what you will.
Stored airtight: few years
In air: few weeks
Dissolved in water: few hours
It also stated that momentary air exposure is fine, ie after a day putting it back in an airtight container will put it back in "few years" category
Make of that what you will.
It should be fine but if you have an untouched one still in it's original package, better to use that to avoid uncertainty. The pinned stability thread is informative and best and only way to know for sure is to test it.
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