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Author: Subject: The short questions thread (3)
Hexavalent
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[*] posted on 16-5-2012 at 09:04


Is the following adequate for handling potassium dichromate (VI);

Goggles
Nitrile gloves
Lab coat

I've read the MSDSs but TBH most of them are quite vague with regards to laboratory handling. I will be using, say, 3g at most at any one time.

Is this sufficient then for handling this compound not in a fumehood?




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ScienceSquirrel
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[*] posted on 16-5-2012 at 09:20


Quote: Originally posted by Hexavalent  
Is the following adequate for handling potassium dichromate (VI);

Goggles
Nitrile gloves
Lab coat

I've read the MSDSs but TBH most of them are quite vague with regards to laboratory handling. I will be using, say, 3g at most at any one time.

Is this sufficient then for handling this compound not in a fumehood?


To be honest, more than enough.
The point is to avoid slopping it on your skin, inhaling aerosols etc.
Most MSDS's are exercises in arse covering.
Think about sulphuric acid; compare say 2.5 litres of hot concentrated acid and 5ml of cold dilute acid.
The MSDS is the same but the hazard associated with the first is a lot greater.
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Hexavalent
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[*] posted on 16-5-2012 at 10:01


Thanks, SS. That confirmed a lot for me, and I have gained my confidence in handling these materials... . the MSDS was enough to put me off initially.

Can anyone who has used this material offer any specific advice on its handling? My salt is in the form of a medium-fine powder. Any good ways to reduce the creation of aerosols?




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barley81
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[*] posted on 17-5-2012 at 10:43


Question: On a 2L bottle of nitric acid, the pouring ring is cracked and the inside of the cap has a few cracks in the liner inside the circle-like impression made by the mouth of the bottle. Otherwise, the cap is fine. Do I need to replace the pouring ring or the cap? If so, where can I buy a new pouring ring?
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[*] posted on 24-5-2012 at 19:28


What is the best haircolor for a person who loves his natural color as much as he loves hydrogen peroxide?

I know i can get cheaper from aquarium and hardware stores, but i'm in rural place and tried the pharmacy already, they have 1% stuff for 4,5€/100ml.
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plante1999
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[*] posted on 29-5-2012 at 16:52


How can-I test for calcium cyanamide without silver.



I never asked for this.
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hyfalcon
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[*] posted on 30-5-2012 at 16:52


Quote: Originally posted by Hexavalent  
Thanks, SS. That confirmed a lot for me, and I have gained my confidence in handling these materials... . the MSDS was enough to put me off initially.

Can anyone who has used this material offer any specific advice on its handling? My salt is in the form of a medium-fine powder. Any good ways to reduce the creation of aerosols?


Just make sure to turn your electrolytic cell off and let it rest a few seconds, minute or two, and let the out-gassing settle before taking your lid off. This will eliminate any aerosols.
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smaerd
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[*] posted on 6-6-2012 at 15:37


Anyone have any tips for drying molecular sieves at home?



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Panache
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[*] posted on 9-6-2012 at 03:53


Quote: Originally posted by smaerd  
Anyone have any tips for drying molecular sieves at home?


the microwave works well followed by application of a vacuum (decent vane pump vacuum or better, be careful though as the first time i tried it the heat of the sieves broke the annealed glass plate of the microwave. place them on any standard dinner plate.

i'm fairly certain you cannot overheat them in a microwave, so use something like a 30min cycle at 50%power. the domestic microwaves simply have one duty cycle which they switch on and off more or less frequently depending on the power cycle.

there is no quick drying procedure for mol sieves, it takes time.

there is a paper around concerning it from like a laboratory education type journal but i don't have it at present.




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Panache
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[*] posted on 9-6-2012 at 03:56


Just checking......does leaving a 240-120V stepdown transformer connected to the 240V supply consume any or much power, it ever so slightly hums and is warm and is really old, big and useful as it has one of every 110/120V plug on it



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watson.fawkes
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[*] posted on 9-6-2012 at 08:06


Quote: Originally posted by Panache  
Just checking......does leaving a 240-120V stepdown transformer connected to the 240V supply consume any or much power, it ever so slightly hums and is warm
If it's warm, it's consuming power, just like a space heater does.

When there's no load on the secondary, the primary of a transformer acts like a choke. The wire within the coil has resistance, just like any other wire. It's not like a dead short, because the coil also acts as a ballast, limiting current.
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Panache
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[*] posted on 13-6-2012 at 05:19


Quote: Originally posted by watson.fawkes  
Quote: Originally posted by Panache  
Just checking......does leaving a 240-120V stepdown transformer connected to the 240V supply consume any or much power, it ever so slightly hums and is warm
If it's warm, it's consuming power, just like a space heater does.

When there's no load on the secondary, the primary of a transformer acts like a choke. The wire within the coil has resistance, just like any other wire. It's not like a dead short, because the coil also acts as a ballast, limiting current.


So i guess that excludes it as a culprit in my ridiculous spike in energy costs from $850 a quarter to ~$2000k.
Personally i think the estimated bills are to blame. Get this because my meter is inside if i'm not around the bill gets estimated. Go back 7 quarters, almost two years, my last meter read, $800, the next six estimated bills $2000-$2500each. I didn't stress i considered it a form of savings.
Finally get a meter reading waiting by the post box every day waiting for my $10K cheque, never arrives.
Two months later decide to give them a call, what happened, i ask, 'Oh if you want a reissued account you have to request one for each bill?'
I ask, but what if you had underestimated? Guess what, bill will issue automatically, i love corporate philosophy. I request bills to be reissued.
Forward twelve months, countless phone calls, million assurances, still no reissued account. i go nuts, following week amended accounts arrive, guess what, over six quarters they claim to have estimated completely accurately, to the cent! i'm laughing at the person on the phone saying come on, their rebuttal 'well its not impossible'
hello electricity ombudsman.




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mineralman
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[*] posted on 16-6-2012 at 02:44


Quote: Originally posted by Roger86  
What is the best haircolor for a person who loves his natural color as much as he loves hydrogen peroxide?

I know i can get cheaper from aquarium and hardware stores, but i'm in rural place and tried the pharmacy already, they have 1% stuff for 4,5€/100ml.


Do dairy farmers use it to steralise the glass in the dairy?
hydroponics mail order 17.5% - 35%

[Edited on 16-6-2012 by mineralman]
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smaerd
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[*] posted on 17-6-2012 at 23:30


In general phenols are not prone to carboxylation/oxidation from typical atmosphere in acidic solutions right? Or should inert atmosphere always be used?

In basic solution they go the way of kolbe schmitt (carboxylation via E.A.S.) but this is because of the phenolate.




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[*] posted on 18-6-2012 at 15:48


Quote: Originally posted by mineralman  

Do dairy farmers use it to steralise the glass in the dairy?
hydroponics mail order 17.5% - 35%


I tried the haircolor stuff, talk about useless stuff.I was under the impression that those would be somewhat diluted H2O2 but the label had at least 15 ingredients, the stuff was horrible for my use.

I just had to drive to city and buy pure stuff from big pharmacy.It cost me 40€ for 1L of 30%, but it was what i wanted in the first place :)
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[*] posted on 24-6-2012 at 23:48


I posted this question in sucrose octanitrate thread but no one replied a proper answer for this thread . My question is What is the detonation velocity of sucrose octanitrate and can it be used as a booster charge in detonators
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weiming1998
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[*] posted on 25-6-2012 at 02:52


Quote: Originally posted by plante1999  
How can-I test for calcium cyanamide without silver.


Calcium cyanamide decomposes on contact with water (http://en.wikipedia.org/wiki/Calcium_cyanamide), so just drop in water. If gases are formed, bubble them through water and pour a solution of Cu2+ ions in. If it is cyanamide, the solution should turn deep blue. Then react the resulting solid with HCl(aq). CO2 gas should evolve, which you can test whether it is CO2 or not with lime-water. No need for silver.

[Edited on 25-6-2012 by weiming1998]
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Diablo
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[*] posted on 25-6-2012 at 21:49


Is anhydrous mgso4 a suitable drying agent for isopropyl alcohol.



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[*] posted on 26-6-2012 at 12:11


Yes, in the sense that it will not react with it. However, if you need it to be really dry (e.g. for synthesis of aluminum isopropoxide or the like) then it is not a strong enough drying agent and you would need to follow up with something else. I have dried IPA with MgSO4 in the course of synthesizing isopropyl chloride, and in this context, where a small amount of residual water is no problem, it worked just fine.




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Diablo
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[*] posted on 26-6-2012 at 14:34


Thank you



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[*] posted on 30-6-2012 at 20:18


Hi everyone!
I have a slightly stupid problem with some household - today I found my bottle of few kg bromine is pretty closed - glass stopper is stuck in this fn bottle. I tried to carefully knock, turn etc, nothing helps. Is there any 'smart' way to open this joint taking on discount all situation?

[Edited on 1-7-2012 by LiHMDS]
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[*] posted on 6-7-2012 at 13:06


In the reduction of carbamates.....in the article,
Preparation of Methyl N-Substituted Carbamates from Amides through N-Chloroamides
Gene A. Hiegel and Tyrone J. Hogenauer

http://www.chembbs.com.cn/bbs/File/UserFiles/UpLoad/20090924...


.....the Chlorinated amine is treated with sodium methoxide to make the methyl carbamate.....

my question, i have sodium ethoxide, can this be used and have the same result?


[Edited on 6-7-2012 by solo]

[Edited on 6-7-2012 by solo]




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[*] posted on 11-7-2012 at 22:44


Quote: Originally posted by LiHMDS  
Hi everyone!
I have a slightly stupid problem with some household - today I found my bottle of few kg bromine is pretty closed - glass stopper is stuck in this fn bottle. I tried to carefully knock, turn etc, nothing helps. Is there any 'smart' way to open this joint taking on discount all situation?


What you have experienced is a "frozen joint". It happens when ground glass joints haven't been lubricated with silicone grease or petroleum jelly. Here's a link to wikipedia article that may help you:

http://en.wikipedia.org/wiki/Ground_glass_joint#Frozen_joint...
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[*] posted on 11-7-2012 at 22:51
Pyrophoric copper?


Hey peeps,
Today I was experimenting with Iron powder divided so finely it was pyrophoric. I synthesised the powder from thermal decomposition of Iron(II) oxalate.

FeC<sub>2</sub>O<sub>4</sub> → Fe + 2CO<sub>2</sub>

I was wondering if the same pyrophoricity could be observed with Copper powder formed with the same method of thermal decomposition of the oxalate salt, or is copper too unreactive to be pyrophoric in this case?
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[*] posted on 12-7-2012 at 02:47


Some guy on this forum has created pyrophoric copper from decomposition of copper acetate, so I think it is possible.
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