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 ...
paracetamol's user avatar
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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, ...
Cort Ammon's user avatar
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14 votes
Accepted

Remove salt from dirt

Assuming you mean NaCl - the common "salt" (chemists call lots of things salt!). If you extract the salt by physical means, it's a physics question. Assuming that the "dirt" is not (or poorly) ...
Floris's user avatar
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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 ...
Jason's user avatar
  • 111
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: ...
Ivan Neretin's user avatar
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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{^...
Jan's user avatar
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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 ...
Weijun Zhou's user avatar
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 ...
Poutnik's user avatar
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9 votes
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Extracting urea from urine

First, from Boundless.com (Chemical Composition of Urine), "Urine is an aqueous solution of greater than 95% water, with the remaining constituents, in order of decreasing concentration urea 9.3 g/L, ...
Ben Welborn's user avatar
  • 1,576
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{...
Buttonwood's user avatar
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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}...
Maurice's user avatar
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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 (...
Poutnik's user avatar
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7 votes
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How to check purity of mercury metal

In case your mercury didn't come with an assay of the supplier, or has been used before, you might want to remove oxidizable metals by repeatedly dripping the mercury though diluted nitric acid and ...
Klaus-Dieter Warzecha's user avatar
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 ...
andselisk's user avatar
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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 (...
Mathew Mahindaratne's user avatar
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 ...
Poutnik's user avatar
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7 votes
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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 ...
NotEvans.'s user avatar
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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 ...
Loong's user avatar
  • 4,813
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 ...
Guillermo Bañuelos Sanchez's user avatar
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 ...
Crowley's user avatar
  • 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 $1-2\%$...
A.K.'s user avatar
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5 votes

To heat or not to heat; distillation?

You obviously already have a general idea of what is going on in a distillation, so I will spare you the picture and everything. Your question can be broken into two parts: Do I need heat for ...
Jan's user avatar
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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 ...
JP Highwater's user avatar
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 ...
Ivan Neretin's user avatar
  • 31.2k
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 ...
Gregg Robinson's user avatar
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 ...
Klaus-Dieter Warzecha's user avatar
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 ...
user50565's user avatar
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 ...
Mathew Mahindaratne's user avatar
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 ...
Poutnik's user avatar
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