![]() |
![]() |
|||||||
Rhodium
(Chief Bee) 10-31-02 02:13 No 374739 |
![]() |
Purification of formaldehyde | Bookmark | |||||
An old bottle of formaldehyde of unknown concentration, with 1 cm of precipitate at the bottom, can this be distilled or something to get 37% formaldehyde solution? |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
SPISSHAK (Hive Bee) 10-31-02 02:16 No 374742 |
![]() |
That sounds like floculation | Bookmark | |||||
Or polymerization, heat it and see if it dissolves. I'm not sure exactly under what conditions formaldehyde floculates but It's a guess. |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
Rhodium (Chief Bee) 10-31-02 02:21 No 374744 |
![]() |
It will probably redissolve with heating, but the ... | Bookmark | |||||
It will probably redissolve with heating, but the concentration is unknown, I'd like to make sure I have a 37% solution. The conditions under which my bottle flocculated was by prolonged storage at 5-10°C. |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
SPISSHAK (Hive Bee) 10-31-02 02:27 No 374747 |
![]() |
I'm not sure how you would test for concentration | Bookmark | |||||
Other than specific gravity, or by seperating the two, I think a certain percentage of methanol is added to formalin solutions to keep it from doing this so it probably is spontaneous. If you heat it to much you'd either A: distill off the methanol B: the methanol would condense on the formaldehyde and produce Methylal. During this process the paraformaldehyde would depolymerize by reaction with water. Depending on what extent you heat it to. |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
lugh (Moderator) 10-31-02 03:01 No 374756 |
![]() |
Paraformaldehyde | Bookmark | |||||
Paraformaldehyde is formed when formaldehyde solution is evaporated, it's probably what's on the bottom ![]() ![]() |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
Rhodium (Chief Bee) 10-31-02 03:10 No 374760 |
![]() |
How can I determine the concentration? | Bookmark | |||||
How can I determine the concentration? Or perhaps I should rather heat a known weight of paraformaldehyde with water instead? |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
lugh (Moderator) 10-31-02 03:48 No 374773 |
![]() |
Concentration | Bookmark | |||||
The specific gravity of formaldehyde is 1.075-1.1081 ![]() ![]() ![]() |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
b159510 (Professional Student) 10-31-02 03:51 No 374775 |
![]() |
~,~ | Bookmark | |||||
How can I determine the concentration iodimetric titration, after 5 minutes add hydrochloric acid and back titrate with na-thiosulfate. or like you said, mix up a new batch, which would probably be easier if you don't have a standardized triiodide solution already made. You don't fool me, Oilman |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
b159510 (Professional Student) 10-31-02 04:27 No 374787 |
![]() |
trioxymethylene | Bookmark | |||||
Paraformaldehyde is formed when formaldehyde solution is evaporated... I've dissolved paraformaldehyde in water, but never evaporated the solution. Isn't that how trioxymethylene is formed? (aka metaformaldehyde, 1,3,5-trioxane) You don't fool me, Oilman |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
lugh (Moderator) 10-31-02 04:49 No 374794 |
![]() |
Triformol | Bookmark | |||||
Yes, as posted in Post 209590 (lugh: "Re: Acquiring Acetaldehyde OTC", Chemicals & Equipment) ![]() ![]() |
||||||||
![]() |
![]() |
|||||||
![]() |
![]() |
|||||||
b159510 (Professional Student) 10-31-02 04:58 No 374797 |
![]() |
my mistake | Bookmark | |||||
The titration I mentioned should still work for an aqueous solution of formaldehyde, even though that isn't the species that actually exists. (What is that called, methanediol?) You don't fool me, Oilman |
||||||||
![]() |
![]() |
|||||||