22
votes
Accepted
Un-denaturing industrial alcohol
(I'm no chemist, but here's my take on it)
Let's see: I’m an alcoholic, and I really hate having to dole out large amounts of cash to purchase your usual "drinking"-ethanol.
So I get this amazing ...
- 18.8k
19
votes
What does it mean for meth or any other compound to be 'pure'?
When a compound is "pure" it means the contents of that compound are exactly what we claim them to be. If something is $99\%$ pure, that means $99\%$ of it is the expected material (in this case, ...
- 1,579
11
votes
What does it mean for meth or any other compound to be 'pure'?
A pure compound is one that does not have anything else accompanying it — and thus is something entirely unreachable if your detection system is good enough unless you’re going for supercooled $\ce{^...
- 68.5k
11
votes
Un-denaturing industrial alcohol
In Soviet Russia, where alcoholism was widespread and homebrewing illegal, undenaturing alcohol was a pretty common thing - a part of national culture, in a way - along with such practices as:
...
- 31.4k
11
votes
Un-denaturing industrial alcohol
The reason criminals don't undenture alcohol is probably because it's cheap and easy to make your own alcohol at home. Plus it's legal in the US (click on G1) and most other English-speaking ...
- 111
11
votes
Accepted
What acid can dissolve thorium dioxide?
Thorium dioxide can be dissolved in the mixture of hydrofluoric acid and hydrochloric acid, as described by Kluger and Lieser in 1981.1
Proceed with caution since hot condensed acid are known to be ...
- 761
10
votes
Is there a method to separate iron from mercury?
As iron is one of few metals not forming amalgams,
Almost all metals can form amalgams with mercury, the notable exceptions being iron, platinum, tungsten, and tantalum.
..it should preferably ...
- 43.3k
9
votes
How to extract pure potassium carbonate from ash?
Historically speaking, potassium derives from pot ash and now potash when -- if there were no geologic sources of $\ce{K2CO3}$ -- woods were burnt in a pot. The addition of water will dissolve $\ce{...
- 30.6k
8
votes
How to extract pure potassium carbonate from ash?
The composition of the wood ashes varies with the nature and the origin of the wood. In the average, it is a mixture of $40$ % - $70$ % $\ce{CaCO3}$, $5$% - $10$% $\ce{MgCO3}$, $5$% - $10$% $\ce{K2CO3}...
- 29.5k
8
votes
Why is desalination waste usually disposed back into the sea instead of converting it into chemical products?
There is no dissolving them again. Ions remain dissolved all the time.
It is like taking
$\pu{11 m3}$ of sea water with salinity e.g. $\ce{30 g/L}$,
producing
$\pu{1 m3}$ of (about) pure water (...
- 43.3k
7
votes
Recrystallisation of dibenzylideneacetone
Armarego's Purification of Laboratory Chemicals suggests using dichlormethane–hexane pair instead of ethanol–water; it also lists crystallization from warm ethyl acetate, ethanol or petroleum ether as ...
- 38.4k
7
votes
Recrystallisation of dibenzylideneacetone
Ethyl acetate is the solvent of choice in Org. Synth. 1932 article. The procedure was submitted and checked. The following is the the full procedure stated in Organic Syntheses.; Collective Volume (...
- 41.2k
7
votes
Concentrating sulfuric acid
Calcium oxalate solubility depends on acidity, as the weak oxalic acid is protonated in highly acidic sulphuric acid.
Additionally, oxalic acid would be dehydrated if sulphuric acid was concentrated ...
- 43.3k
7
votes
Accepted
How can I filtrate Pd2(dba)3 and P(o-tol)3? (Celite filtration failed)
Your question is actually two: how do I remove residual catalyst, and how do I remove residual ligand. The situation is complicated yet further by the fact that both catalyst and ligand are capable ...
- 17.2k
7
votes
Why is kerosene being used in PUREX (plutonium uranium reduction extraction) as a solvent?
The actual extraction agent in the Purex process is tributyl phosphate (TBP). It is one of the most versatile extraction agents for many inorganic ions and has been made the basis for a number of ...
- 4,824
6
votes
Removal of tetrabutylammonium from an organic reaction
I know it is a relative old issue but I had the same problem with nucleosides during my PhD. I tried a wide range of reagents but all of them lead to the decomposition of compounds or no reaction ...
6
votes
Un-denaturing industrial alcohol
As @matt_black and @Aaron Abraham suggested, cleaning the denaturated ethanol is difficult and expensive. You don't know, what chemicals other than ethanol and methanol are in the solution and in what ...
- 199
6
votes
How do chemists measure purity in high purity metals and other reagents?
As the comments alluded, to analyze purity at high purity, you analyze the impurities. I'll use XRF for this example, but ICP, MS, HPLC, or other methods could work in the same way.
With XRF's $1-2\%$...
- 12.7k
5
votes
Accepted
Why are 'table salt and sugar are both terrible candidates for recrystallization'?
The solubility of $\ce{NaCl}$ has very poor temperature dependency. If you dissolve it at $100^\circ\rm C$ and precipitate at $20^\circ\rm C$, you'll essentially lose about 35 g to purify 3 g. Even ...
- 31.4k
5
votes
What does it mean for meth or any other compound to be 'pure'?
Organic reactions (reactions involving fairly complex compounds of carbon) like the ones used in drug synthesis, are notoriously complicated and almost always produce various side-products and ...
5
votes
Difference between lab-grade and food-grade purity?
Background: I'm a chemist and have worked for companies in Pharma, Research Chemical Supply, and Dietary Supplements.
Lab Grade is different than Food Grade, yes. Normally Food Grade is a LOWER ...
- 51
5
votes
Accepted
How to reduce Tin Oxide
The video shows the "purification" of zinc metal (probably covered with an oxide layer) by heating/reacting it with powdered carbon.
This is a very common process to reduce metal oxides to the ...
- 44.1k
5
votes
Accepted
How does activated carbon trap impurities?
Never forget to interpret in terms of physical/chemical forces, by order of energy: van der Waals, hydrophobic (pseudo forces), hydrogen bonds, disulfide bridges, covalent, electrostatic (for the most ...
- 76
5
votes
Accepted
Techniques to extract lipids
Casein is a mixture of phosphoproteins found in milk that accounts for approximately 80% of the total protein content of cow milk (cow milk contains 3.3% total protein). Hence, it is easy to prepare ...
- 41.2k
5
votes
How to extract pure potassium carbonate from ash?
It seems that by partial crystalization, it can be somewhat purified as the most soluble salt, but cannot be easily purified to high purity degree. It may be andvantageous to crystalized near water ...
- 43.3k
5
votes
Accepted
Synthesis of anhydrous sodium tungstate
Hoermann [1] prepared anhydrous sodium tungstate by melting the 1:1 mix of sodium carbonate and tungsten(VI) oxide (and, subsequently, growing single crystals); alternatively, he proposed prolonged ...
- 38.4k
5
votes
Accepted
Purifying ferrous sulfate
You better make your turbid solution boil with some iron wires $\ce{Fe}$ and a bit of sulfuric acid. The turbidity observed in your solution is due to a mixture of two precipitates containing $\ce{Fe^{...
- 29.5k
5
votes
Accepted
What chemical reactions takes place in purifying acetylene?
The main impurities of $\ce{C2H2}$ are : 1) $\ce{H2}$ destroyed by $\ce{MnO2}$, 2) $\ce{NH3}$, destroyed by copper sulfate, mercury chloride and and ferrous chloride, 3) $\ce{PH3}$, destroyed by ...
- 29.5k
4
votes
Accepted
Does UV water purification cause cancer?
Is it possible that this use of UV radiation may lead to cancer in humans?
No!
The lamps used for water treatment are usually low pressure mercury vapour lamps. These lamps emit in the UV-C range ...
- 44.1k
4
votes
Accepted
Confirming the presence of 4-bromoacetanilide during bromination of acetanilide
I advise against fishing in the mixture in this case. Try to isolate the product, purify it and determine its properties.
Have a look at the melting points of the starting material and the possible ...
- 44.1k
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