# Tag Info

20

(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 idea to separate the ethanol by distillation (methanol has a lower boiling point than methanol, so what I'll really be doing is distilling out the methanol, ...

17

Fractional distillation can work, but the separation per round of distillation is very low so you would need a very large multi stage process to achieve significant separation. Nobody uses direct distillation to produce heavy water as there are better chemical processes that achieve higher enrichment per stage, for example the Girdler sulphide process.

11

Add Calcium Chloride to destroy the azeotrope. Then distill and capture the vapor phase. See the second method "Extractive Distillation" here: http://www.jacobs.com/uploadedFiles/wwwjacobscom/20_Learn_About_Us/25_Products/252_Chemetics/Hydrochloric%20Acid%20Concentration.pdf (Obviously, proper equipment and safety precautions are essential.)

10

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 countries. You can get equipment kits from anywhere between 50 and 200 USD (more expensive kits will get you tools that make things easier or improve quality and add ...

10

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: drinking straight down various non-food grade products containing ethanol or extracting ethanol from them or stealing ethanol from industrial processes or, well, ...

10

Irrespective of the potential hazards to an inexperienced chemist attempting distillation of hydrochloric acid, especially absence of adequate safety measures such as a fume hood, in this case, distillation will not result in a higher concentration of acid. Hydrogen chloride and water form a constant-boiling mixture (azeotrope) at ~20% HCl, which is what you ...

8

This is a good question, but no, there is no azeotrope in any isotopic mixture, as an azeotrope requires non-ideal mixing of two components to form a minimum or maximum critical point on the plot of total vapor pressure as a function of composition as shown in Figure 1 below. Isotopic Mixtures have a near-zero enthalpy of mixing, making isotopic mixtures ...

7

Isopropanol is not one of the notorious peroxide formers, but it will eventually do so in the presence of oxygen (with or without light - the process is autocatalytic). When I was a graduate student TA in an organic chemistry class, isopropanol was a distillation "unknown". However, the "unknown" bottle had probably been in existence for 20 years and was ...

7

The purpose of the vacuum jacket is to provide insulation of the column from cooling by ambient lab air. You don't want to have to heat the "pot" (the flask containing the crude material you want to purify) any more than you have to, otherwise heat sensitive material in the pot may degrade and turn to tar. Imagine if you cooled the exterior of your ...

7

For a comparison of different methods, including distillation and the Girdler processes, have a look at Heavy Water: A Manufacturers’ Guide for the Hydrogen Century In this 14 pages document a survey of the different available processes is given. The distillation of water, as suggested by the OP is included. That process is the easiest but requieres huge ...

6

Don't bother with a powered pump: Get a water aspirator (I recommend the $20 Humboldt H-12020, which uses 10mm or 3/8" inner diameter tubing just like your glass), connect to faucet, and using utility water (1-2 gallons/minute) it can pull over 500 torr, which should be adequate for your applications. Sure, you're flushing away a lot of water, but you don't ... 5 If you have the vapor-liquid phase diagram, then it is easy to determine the vapor composition above a boiling liquid mixture (which should approximate the composition of your first drop in a simple distillation). I'll assume you diagram looks like the one below, which is from the Wikipedia article on vapor-liquid equilibrium(and is mostly at the physical ... 5 In principle, it is difficult to distill salts (ionic compounds). Therefore you first make sure that you have a free base in the solution. This is guaranteed in alkaline solution. For the steam distillation the compounds should be immiscible, which is another reason for having a free base. Let’s compare boiling points and solubility for aniline and its salt: ... 5 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 concentrations. Selective absorbtion using zeolites, as @SteffX suggested, is also blank. You don't know what to filter out. Maybe using regenerative filter ... 5 Distillation alone has been used on an industrial scale to produce heavy water, but it requires a multi-stage process and uses a lot of energy due to the small difference in boiling points. That would seem to confirm that water and deuterium oxide do not form an azeotrope. 5 Boiling a water mixture doesn't always produce pure water. Boiling a solution of salt and water (or evaporating the water) will separate the salt from the water, but those are compounds with very different properties. In the making of distilled alcohols (Ethanol), the vapor phase has more alcohol than water. Repeated distillations can increase the ... 5 You have multiple options. All of them assume that the distillation setup is empty, at ambient pressure. Of course, like mentioned in the comment by @Waylander, put a little of (silicon) grease on the glass joints prior to the distillation, just enough that they become transparent. There are multiple kinds of grease, suitable for different temperatures / ... 4 There is no such point when the first solvent is completely distilled and then the next one starts. From the very beginning, both solvents boil together, though the vapor initially is relatively enriched with the lower-boiling one. The cutoff point is set somewhat arbitrarily. And yes, the answer surely has something to do with temperature, because ... 4 As above, your labor all by itself (even if you are grad student) is worth more than the sulfuric acid. As a pedagogic exercise, run the solution down a strong anion exchange resin washed OH-. Only glucose comes out. Recover the sulfuric acid by displacing it with phosphoric acid. 4 Sodium hypochlorite is not carried over into water by distillation. Instead, at high (~100°C) it decomposes, primarily to sodium chloride (i.e. table salt) and oxygen gas, but also possibly to trace amounts of chlorate. You could neutralize the hypochlorite by mixture with stoichiometric amounts of hydrogen peroxide, which cause immediate release of ... 4 After producing nitrogen by distilling air, how is that nitrogen used with the oxygen to yield nitrous oxide ($\ce{N2O}$)? It's not clear to me that$\ce{N2O}$is produced from$\ce{N2}$: Rather, it appears that commercial quantities of$\ce{N2O}$are produced by thermally decomposing ammonium nitrate: $$\ce{NH4NO3(s) -> N2O(g) + 2H2O(g)}$$ as described (... 4 First of all, make absolutely sure that there is nothing blocking the path between the distillation flask and the final vent, and that all the joints are tight. When beginning the distillation, you should be able to view the condensation line move up within the apparatus after the mixture begins to boil. If it moves up toward the thermometer, but then stops ... 4 In order to both achieve sufficient separation and minimize loss during fractional distillation, you want a large inner column surface for optimal contact of the vapour phase (upstream) and the liquid phase (downstream) a rather small inner column volume Often, these destillation are performed using a Spaltrohr distillation apparatus. Here, the vertical ... 4 Relying on the difference in vapor pressures of$\ce{HDO}$and$\ce{H2O}$is equivalent on relying on the equilibration of$\ce{HDO(g) + H2O(l) <=> H2O(g) + HDO(l)}$The fractionation factor$\alpha_{\ce{D}(l)/\ce{D}(g)}$for this reaction is 1.015 at STP. Deuterium ($\ce{^2H}$or$\ce{D}$) is separated from protium ($\ce{^1H}\$) commercially, ...

4

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 vapourisation? Do I need cooling for condensation? I am going to address them one after the other. Vapourisation As you probably also know, reducing pressure is ...

4

The article "The Chemist's War" http://www.slate.com/articles/health_and_science/medical_examiner/2010/02/the_chemists_war.html goes through the various changes to denaturing agents used after the passage of the 18th amendment (Prohibition). I think the cost/benefit tradeoff still makes it unattractive

4

Silicon grease is the one we used normally. But, your post indicates that grease hasn't worked for you. Any adhesive tape wouldn't work because it will increase the risk of leaking (specially when you are refluxing). However, we have used PTFE sleeves between joints, which have worked wonders. These sleeves are not cheap but very durable and reusable. ...

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