The process of rendering something pure, clean of foreign or undesired elements.

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196 views

Textbook chemistry vs Real life chemistry and impurities

Long ago when I took chemistry courses in high school and lower, chemistry seemed so simple and elegant. All equations and exercises involved pure elements, pure compounds, with a very clean ...
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35 views

Mechanism of protein precipitation with TCA

In practice, TCA (trichloroacetic acid) is widely used for quantitative protein precipitation, but so far I have failed to discover the exact mechanism of TCA action. I highly doubt it's just the ...
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31 views

opperating a distillation column far from flooding

I know that flooding will ruin the performance of a distillation column. There are many correlations (Eckert, kister, billet, etc.) that will tell you when a column will flood based on your fluid ...
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56 views

How to clean copper(II) sulfate crystals from sulfuric acid?

I am going to prepare copper(II) sulfate by electrolysis with sulfuric acid for crystal growing. How would I separate the copper(II) sulfate from the sulfuric acid left over from the electrolysis ...
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1answer
26 views

How to recycle olive oil manufacturing wastes?

The fact that only 20% of the olive used to make olive oil becomes olive oil and the other 80% is spread between hard wastes and liquid water wastes made me want to ask this question. Isn't there a ...
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27 views

What [if anything] is special about the boiling process of purifying water (excluding temperature)?

I know that water boils at $100~^{\circ}\rm C$. I also know that the standard way to purify water is to boil it for roughly a minute. What I'm curious about is, what properties of the boiling process ...
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33 views

How to remove dichlorometane from water?

I will have water that have been through dichloromethane. Doing so, the dichlorometane (solubility $2~\%$) will contaminate my water by forming an azeotrop which will have a $38~\mathrm{^\circ C}$ ...
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57 views

Clarification on Recrystallization concept

Any help you could provide me would be greatly appreciated and I thank you for reading (even if you don't comment) I am in an organic laboratory and as a 3rd chemistry major these concepts usually ...
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28 views

Purification Problem in Darzens Method?

We know that the Darzens method of substitution works on $S_n i$ and is considered the best method in terms of yield of product. Also the side products are $\ce{SO_2}$ and $\ce{HCl}$ so the ...
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36 views

Is there a way to concentrate the vitamin content of a particular food?

I'm looking for a way to extract vitamins out of common food sources of, well, vitamins. Let's take, as an example, Vitamin A which is commonly found in carrots. A carrot (weighing around 60g) should ...
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33 views

Cell voltage required for refining copper

If you put Zinc or Iron solids into aqueous copper (II) sulphate solutions, copper solids form spontaneously due to the fact, that Zinc/Iron oxides into ions more willingly than Copper does. And if ...
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135 views

How to prepare glacial acetic acid from sodium acetate?

What would be the most practical process to prepare glacial acetic acid from sodium acetate? I'm thinking to react the sodium acetate with an acid to convert the solution to acetic acid and sodium ...
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1answer
63 views

Flavor components of high end vodka?

I always thought vodka was just alcohol and water, and that the ideal vodka was one lacking all flavor components characteristic of the grain or potato mash that it was distilled from. I once saw a ...
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30 views

Does precipitated copper carbonate contain impurities

I recently performed a double replacement reaction between copper sulfate and sodium carbonate to yield copper carbonate as a precipitate. I then filtered the precipitate, but I noticed that the ...
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31 views

Removing harmful gases from automobile exhaust using electrostatic precipitation

If I attach an electrostatic precipitator to a car's exhaust - and also make the smoke pass through an area containing $\ce{NaOH}$ in order to absorb sulfur dioxide - does that mean that the smoke ...
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2answers
83 views

Dry Hydrogen Production

I am building a set-up to produce a controlled flow of dry hydrogen. I'm aiming for around 99.5 percent purity. Am I right in thinking a PEM cell and Deterite drying tube should be fine for this? Or ...
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416 views

What makes oceanic desalination so expensive?

What specifically makes oceanic desalination so expensive?
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146 views

Purification of Ethanol

In Vogel's organic book, they have mentioned that in the Lund and Bjerrum method of purification of ethanol, magnesium is added, which forms ethanolate. But they said to activate the magnesium first ...
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139 views

Comparing purity grades for ethanol

I am trying to determine if the following two grades of ethanol are equivalent: Ethanol absolute, 99.8% Normapur AR (Analytical Reagent) Ethanol alcohol, pure ACS reagent, ≥99.5% Information on ...
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61 views

How can I purify ethanol from formic / boric / salicylic acid?

I need some ethanol pure and strong enough for technical purposes (fuel, solvent, cleaning agent, dissolving rosin for soldering flux, etc.). Food quality is not required though, denaturated one is ...
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1answer
133 views

Old, red sample of sodium tetraphenylborate—why it is red?

I have a really old sample of sodium tetraphenylborate. It should be white, but it is red. Does anyone know what was formed and how it influences precipitation of cations in water?
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64 views

Obtain precipitated iron?

Is it possible to obtain pure, precipitated iron with no oxidation by some chemical process? Alternatively is it possible to electrically purify iron using an anode and cathode?
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40 views

Make pure phthalocyanines from phthalocyanine dyes

We need a pure copper phthalocyanine for our experiments. Of course, we can buy it from Sigma Aldrich, but this means we'll have to wait a while. In local area we can buy only dyes which are about 98% ...
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235 views

how to separate gamma-butyrolactone from N-methyl-2-pyrrolidone

Since these two chemicals have different freezing temps (pyrrolidone is $-11~\mathrm{^\circ F}$ [$-24~\mathrm{^\circ C}$] and $\unicode[Times]{x3b3}$-butyrolactone freezes (also called melting) at ...
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1answer
118 views

Is the following paragraph about steam distillation accurate?

I've been struggling with the various methods of purification of organic compounds. If a question comes up in my examination, asking me to explain steam distillation in my own words, I'd like to know ...
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1answer
158 views

How does the production of pure, crystalline silicon via the Czochralsky or Siemens process?

I have a few questions regarding the production of pure, crystalline silicon: As far as I know Silicon usually appears in nature in the form of sand or $\ce{SiO2}$ and then is split apart and brought ...
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1answer
68 views

Removing trace amounts of water from agricultural grade anhydrous ammonia

Agricultural grade anhydrous ammonia (liquefied gas) contains 2000 ppm $\ce{H2O}$. What would be the process to remove this water to obtain refrigeration grade (<100 ppm $\ce{H2O}$) anhydrous ...
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92 views

How to purify water with activated carbon?

If I am not mistaken, distilling water does not remove all possible impurities. Chemicals with boiling points less than $100\ \mathrm{^\circ C}$ will be transferred as well. Does the usual tap water ...
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104 views

How do I purify the resulting compound after a nitro- to amine-group reduction?

I have an aromatic compound that I reduced with either $\ce{Fe + HCl}$ or $\ce{Sn + HCl}$. How would you choose to go about extracting the compound? I'm thinking to dry off all the $\ce{HCl}$, ...
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3k views

What would be the most suitable solvent for a single-solvent recrystallization?

The compound in question is acetanilide, and the solvents in question are: water, ethanol, and ethyl acetate I was thinking all three would be suitable since upon experimentation, acetanilide ...
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907 views

Recrystallization and purification techniques for getting a pure sample

Could someone explain in detail as to why exactly recrystallization gives a more pure solid solid sample? As well as why is would be better 'technique' to allow for the crystal to form slowly? I was ...
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302 views

HCl/diethyl ether + Nitrogen?

Just wondering if anyone can tell me why bubbling nitrogen through a solution of $\ce{HCl}$/diethyl ether catalyst would remove said mix from my solution. My current thought is that the $\ce{N2}$ ...
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1answer
96 views

Chlorination of Water

Does passing chlorine gas through water form hydrochloric acid or bleach? Also, will a mixture of hydrogen and chlorine gas from electrolysis of brine do the same?
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602 views

How to obtain pure aniline from a mixture of phenol and aniline?

There is a mixture of aniline and phenol. I need to obtain (just the procedure) pure aniline. So I think the mixture should heat with Zn powder(to convert phenol to benzene) and then I thought to ...
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219 views

How to crystallize out reaction mixture from DMF?

Reaction was carried out in DMF, and TLC shows that the reaction has completed. But how to separate reaction mixture i.e. product from DMF? Edit Steglich Esterification was carried out and the ...
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99 views

Solar still and how it works

I use a solar still that holds 182 cubic feet of water. Here is how it works: There is an insulator on both sides of the metal bowl. On the outside it covers the whole thing. on the inside it covers ...
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1answer
243 views

Recrystallization of two unknown compounds?

I managed to separate a binary mixture(in solid form) of two unknown substances into two individual solid compounds. For the separation, I used an acid-base extraction with dichloromethane, NaOH, and ...
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743 views

Why is crystalline aspirin washed with chilled water in the purification process?

Take as example this or even better this: Wash the crystals with 2-3 ml of chilled water. Why does the aspirin need to be cooled down? And why do we wash the aspirin with chilled water?
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111 views

What is a good way for a laymen to purify alcohol to near 200 proof?

I'm making herbal and medicinal mushroom tinctures and extracts. Normally I'll use everclear but it isn't cheap and 95% alcohol. Also I don't know what that other 5% is. Is it just water? Is ...
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136 views

Different techniques of distillations

I know that fractional distillation is used to separate two liquids that are miscible in one another and have close boiling points. However, I am really confused about vacuum and steam distillation - ...
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40 views

The proteins “eluted” or “were eluted”?

In describing proteins, I've written "the proteins detached from the [Ni-IDA] matrix and were eluted from the column" Should I use "were" or can something simply "elute" ?
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1answer
779 views

How to make artificial sea water

My 7th grader is embarking on a long-term science project and I'm on tap to "help." He is showing a strong interest into finding ways to get drinking water to the masses. His idea is that we need to ...
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1answer
163 views

Best place to take off vacuum for distillation

I have seen vacuum take-off adapters that are essentially plugs, which could be placed at the top of a three-way above the fractionating column, and also straight and bent vacuum take-offs with an ...
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1answer
408 views

Does caffeine isolated from coffee contain harmane?

I'm not sure whether the caffeine contained in otc caffeine pills is made synthetically or isolated from coffee and other plants, but if the latter is the case, is it likely that it contains the ...
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4k views

Azeotropes and separation by distillation?

I have just recently learnt the theory of fractional and normal distillations and the basics of maximum and minimum boiling azeotropes. Most books say that the components of the mixture forming an ...
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15k views

How does alum improve the settling of particles to produce 'clean' water?

How does the addition of alum — potassium aluminium sulfate or $\ce{KAl(SO4)2}$ — help settle the dust particles in water? There was such a statement in my Year 9 textbook, and so I was wondering how ...
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155 views

Removing titanium from tantalum crucible

I'm trying to remove titanium filling from a tantalum crucible for a high-temperature effusion cell. I've managed to get a majority of the material out with tweezers, but some remains and is ...
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1answer
486 views

Is it safe to condense water into a liquid nitrogen trap?

I'm trying to remove water from an imidazolium salt (i.e. dry the salt). However I want to know if it is safe to remove the water under vacuum. Is it safe to condense water into a liquid nitrogen ...
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226 views

How are pure substances (elements, compounds, etc) produced?

How are large quantities of the substances we use in the lab generally produced? (As in the process from getting the stuff out of the ground to use in the lab) How 'pure' are they? Also: is it ...
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73 views

How are arsenic compounds removed from drinking water?

I used to live near a volcano where the groundwater contains naturally occurring arsenic compound. Since $\ce{As_20_3}$, $\ce{As_2S_3}$, and $\ce{As_4S_4}$ are predominantly occurring in drinking ...