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Author: Subject: Everyday Chemistry (provisional)
DraconicAcid
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[*] posted on 28-7-2020 at 21:37


I've got my son (a 16-year-old version of me) helping me in the lab, videoing some experiments so that this semester's social-distancing rules won't kill off our college's chemistry labs. I am very proud to be able to give him the lab experiences that I wished I could have had at that age.

In addition to lots of esterification reactions, TLC, the copper carnival, and distillations, we also prepared some hydrated copper compounds (for the students to determine the degree of hydration in). Just for fun, we decided we'd make copper sulphamate (following this prep: https://prepchem.com/synthesis-copper-sulfamate/ ), since I saw a lovely sample of it on Instagram, and copper(II) sulphanilate. The latter did not work at all- after reducing in volume, it started to crystallize and solidify as it cooled, so we didn't need to triturate it with acetone. Recrystallizing it from water/methanol gave pale blue crystals which turned white when washed with methanol- clearly not very coppery. According to this: https://patents.google.com/patent/US3321273A/en it's probably ammonium bisulphate.

The copper(II) sulphanilate seems to have worked, giving a nice green precipitate from the reaction of copper(II) acetate with sulphanilic acid (eventually- some boiling down of the solution was required. I'm hoping no hydrolysis of the anion took place).




Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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HeYBrO
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[*] posted on 28-7-2020 at 21:48


Quote: Originally posted by j_sum1  
Distilled some otc isopropyl alcohol. Seemed to be already high purity. Head temp held rock steady and I discarded only a couple of mL of heads and tails.

IPA is not quite the ubiquitous substance here that it is in the US. Nice to find such good quality.


Nice, did you dry with NaOH?

You can get relatively large amounts from eBay and if you want smaller quantities (ca. 250 ml) you can buy 99% isopropanol from jay car (at least in vic...). I also noticed it at pharmacies as a 60% solution but it was stupidly expensive.
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j_sum1
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[*] posted on 29-7-2020 at 02:33


Quote: Originally posted by HeYBrO  

Nice, did you dry with NaOH?

I could say that I didn't feel the need to. But the truth is that it did not occur to me at the time. But I am not doing anything water sensitive with it anyway.

My main reason for getting it was because I needed a secondary alcohol for teaching. I had a really nice lab session with a handful of kids just over a month ago. Alcohol oxidation with acidified dichromate was one of the things covered.
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[*] posted on 14-8-2020 at 06:39


Low on ammonia solution. So I spent an evening making a batch. Finished up ith 222mL at 22%.
Nitric acid tomorrow.
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[*] posted on 15-8-2020 at 02:50


J_sum1 I am not quite ready to make nitric acid. I’m sticking to simple reactions within my limits :) Fortunately 70% nitric acid and ammonia solution are both available locally.

I’ve returned to cyanurates while waiting for more glycine; nickel carbonate and cyanuric acid have been stirring in the shed since Friday.
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[*] posted on 31-8-2020 at 22:37


do believe my CH3NH3 has turned out. No MP test, but slightly "fishy" and VERY hygroscopic. Also give a blue reaction to Simon's reagent.



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DraconicAcid
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[*] posted on 10-9-2020 at 21:05


So I was trying to get some nice crystals of copper(II) lactate, but it seems that it forms a mixture of different hydrates and/or crystallizes with excess lactic acid. So I said to heck with this- I'll precipitate it out as the carbonate. Added potassium carbonate, and got a very dark blue solution, matching the description of an anionic lactate complex that I recently read about. Bother.



Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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[*] posted on 11-9-2020 at 12:05


Just now I trying to make potassium iodate by permanganate method according to recipe from my high school. Right now reaction is done and I filter manganese dioxide from solution. And it is pain in the ass. I filter it through coffee filter and solution goes through incredibly slowly. Filtrate is still brown, but most of MnO2 remains in filter. After filtration I'll do another filtration through finer filter which retain fine particles of MnO2.



If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

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[*] posted on 11-9-2020 at 17:08


Today was Cobalt day for me and the family.

I added NaOH to CoSO4, and got a nice blue precipitate.

In a separate container, I added CoSO4 to excess NaOH although the precipitate was blue for a moment, it quickly turned pink.

Gravity filtered both of them with coffee filters (blue solid filtered quickly, the pink solid filtered extremely slowly) and now letting them both dry. Will heat them both to convert to Cobalt Oxide, then I'l weigh and then add to my compound collection. I'm curious if either the pink or blue form "converts" to the other during these processes.

I also added CoSO4 to excess NH4OH, and the solution turned brown. Adding some NH4OH to CoSO4 gave a blue precipitate, like adding NaOH did.
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[*] posted on 11-9-2020 at 20:53


Co(OH)2 will react with atmospheric oxygen to produce brown CoO(OH).

Something about blue and pink form is on wiki:

https://en.wikipedia.org/wiki/Cobalt(II)_hydroxide

Brown soluble complex with ammonia is [Co(NH3)6]2+ and it's slowly oxidized by oxygen in to [Co(NH3)6]3+.




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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