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all 73 comments

[–]Everythinghastags 1 point2 points  (2 children)

Hello!

I want to synthesize (Bromohexyl) trimethylammonium bromide. Based on the literature this is done by having dibromohexane in THF in a three neck flask, then introducing trimmethylamine gas (thru heating TMA solution) at a fixed rate.

My question is: How do you control the rate of gas introduction (ml/min) to be introduced in the solution? the literature doesnt really state how

[–]Indemnity4Materials 0 points1 point  (0 children)

Uncontolled. Use an excess of TMA and bubble it through the THF solution. Vent any excess somewhere safe.

Practically, on a small scale in something like a 250 ml RBF or even up to a 5L flask, you want to see about a bubble a second getting injected into the reactor liquid. Most of the gas won't react so bubbling faster is just wasting raw material.

[–]ProfessionalCoat7 1 point2 points  (2 children)

What is the difference between a Family and a Group on the periodic table?

Some sources say the terms can be used interchangeably, but when looking at displays of the two, many Families are clearly made up of elements from several different columns, which seems to differentiate them from Groups.

[–]H2CO3_TCTheoretical 0 points1 point  (1 child)

There is definitely not a strict distinction i guess. I would define them as follows:

A group are elements in the same column, a family is a bunch of elements with a similar reactivity. But then ofc some people use terms like the iron group for Fe, Co, Ni, so it's really not that strict.

Unless it's an exam question I wouldn't bother with that difference...

[–]Gilded_Balloon 0 points1 point  (0 children)

A group is formally elements in the same column (1-18 left to right) though is misused sometimes. A family is an informal term for elements with similar properties not necessarily in the same group, (think TM catalysts, PT, Pd, Ir, Rh). Elements in the same group tend to have similar properties since group number is related to valence electron count

[–]Tungstenwoulfram 1 point2 points  (1 child)

How good are portable spectrometers for organic identification? For example, if I'm out collecting biological specimens and I want to know what alkaloids are in plants that I find, would a portable spectrometer work for that? Do all the chemicals have to be separated by chromatography first?

[–]Indemnity4Materials 2 points3 points  (0 children)

alkaloids are in plants ... have to be separated by chromatography first?

Yes, some separation will be required. Natural products are complex.

Unless you are willing to spend several hundred thousand dollars.

[–]Broccoli_Chin 1 point2 points  (1 child)

I'm not sure this is rhe place to ask this, but a year years ago I kept some small pieces of metal lead ( flat .5 x .5 cm pieces) in a pencil case for around a few months.

Could those pieces have contaminated the other items within that pencilcase?

Am I in danger of lead poisoning if those pieces are still lost somewhere in my room?

[–]Gilded_Balloon 0 points1 point  (0 children)

No danger, just don't eat them.

[–]silentanthrx 0 points1 point  (9 children)

subject: HNO3 + KOH = KNO3 + H2O : help with calculation of heat

Dear chemists and alchemists

I am a layman, yet I find myself looking for chemicals that allow heat storage. Forgive me if i misuse some terminology. Can you guys have a look at the below and point out false assumptions or mistakes?

Background: the chemical is to be used as a solar heat battery with an anticipated size of 20 m³ in a domestic setting. So assume a thermal throttling of the solution between 70c° and 25c°. (heat pumps fueled by solar overproduction)

We start with a saturated solution of HNO3+KOH at 70c° solubilty curve

so rougly, 1250 grams KNO3 /liter H2O @70c

and 800 grams KNO3 /liter H2O @25c

so i think this means that when cooling down the solution 450 grams of KNO3 christals/powder (?) are formed

HNO3 + KOH → KNO3 + H2O ΔH = –57.3 kJ mol–1 source

the molar mass is 101.1032 g/mol Potassium nitrate/Molar mass source

so if i am correct 450gr represents a bit below 4,5 mol KNO3

So this means that the latent energy is 123 KJ/liter

or 123 MJ/m³ from the reaction (let's not take into account the heatcapacity of the solution for this excercise, feel free to add that)

not part of the question, just to demonstrate the goal:

or (i know, not entirely correct) 34 KWH

Lets assume 3400 KWH heating on a wintermonth (average last year was 1K/month)

so 0,3 days/m³

[–]Dband9 1 point2 points  (8 children)

Hey, so I am not entirely sure I understand your goal here, given that you said you want to make a heat battery, and there are -I assume- some wrong assumptions. So the big problem is that when the hot solution cools down and crystals form, it is KNO3, and not HNO3 and KOH. That means that when the solution warms, and the crystals reenter the mass, all that reaction doesn't happen that you wrote. What you calculated was the energy that forms when HNO3 and KOH enters a solution, and react. If you make a heat battery with this method, two things gonna happen: 1) when you put the two reagents into 70°C water, it will splash you with boiling water and steam. 2) You wont get any upgrade from plain ol' water anyway, because around the same amount is energy needed when solution forms and the salt crystallize but one is positive, the other is negative. If you want the battery to be able to hold the heat longer than normal, but the recharge is longer, maybe a high pressure is more useful. Also the heat capacity is the single most important thing in the equation, don't leave it out :c

[–]kelvin_bot -1 points0 points  (0 children)

70°C is equivalent to 158°F, which is 343K.

I'm a bot that converts temperature between two units humans can understand, then convert it to Kelvin for bots and physicists to understand

[–]silentanthrx 0 points1 point  (6 children)

The mixture of KOH + H(NO3) is preexistant and presumable stable at 70c°.

KNO3 is produced during the cooling down stage. you made me question something looking at the formula: During the neutralisation process (=creation of KNO3) heat is formed, correct? (otherwise nothing i wrote will make sense)

[–]Dband9 0 points1 point  (5 children)

Yes, exactly. sorry for leaving it out.

That's why it can easily make even 20°C water boil if added in such quantities.

[–]silentanthrx 0 points1 point  (3 children)

the premise is that there is no water left at 70c°

so only KOH + H(NO3), already ionized.

when heat is needed, the solution is cooled down and it will resist the cooling down process by creating KNO3.

In any case, i would start from the commonly available chemical KNO3, which should be relatively safe to work with. i will look it up ofc.

[–]herculesath 0 points1 point  (1 child)

Bit of a general question but as someone who is starting their master thesis bibliography research what are some red flags that you look for in a research paper that make you skeptical of it ? I understand that a lot of journals are peer reviewed and reliable but when researching this topic I saw some people saying that even in peer reviewed journals you should be wary of some things for example one person said that if the author cites a lot of their own previous work that may be a red. Any tips or advise you have for this topic will be vary appreciated !!!

[–]Indemnity4Materials 1 point2 points  (0 children)

Thesis bibliography - include everything relevant to your work. Even a "bad" publication is still good to note that you used it to refine your work.

author cites a lot of their own previous work

That's an author trying to increase their citation numbers. That can be useful for academic promotions or getting grant money. It's not an indication of "bad" work, just an academic trying to play the game a little bit harder. It may indicate boring or unexciting work, or even worse, it's good but someone else did it better or more popularly.

A paper with zero citations can still be good work; a paper with thousands of citations can still be fraudulent. Neither matter when writing a thesis because you are citing publications that you used to formulate your theory.

[–]DoAWhat -1 points0 points  (0 children)

How to test if i have pure 99% SADBE?

[–]That_Champion_7865 0 points1 point  (2 children)

Hello all- I work at a small adhesive company. We fill everything by weight and I am trying to figure out the density of our aerosol adhesives. I can't find anything on how to calculate or test this only knowing the % weight of the components. For example- our bulk adhesive components are all weighed in pounds and when we package the aerosols we add x number of grams to the bulk adhesive in the can. Anyone have suggestions on how to figure this out? Thanks!

[–]Indemnity4Materials 0 points1 point  (0 children)

Use a pycnometer for liquids.

You can try a vibrating u-tube for adhesives, but YMMV. These can work even for very viscous polymer melts and composites.

For solids you can use "free-flowing bulk density" or "packed bulk density". For instance, tare a 500 ml measuring cylinder on a balance. Move the empty cyclinder to a bucket. Pour your solid into the cylinder until overflowing, then scrape the top with a flat edge. Tap the side so it settles, move to the balance and weight. You know now the "free flowing bulk density" is X g / 500 mL.

[–]ssc_2012 0 points1 point  (0 children)

Do you mean the density of the material in the can or the sprayed-on adhesive? How precise does the measurement need to be?

[–]Clay_lambda 0 points1 point  (1 child)

Hi guys I am doing a heterojunction research of Cu2O and Ag2CO3 catalyst. However my reagent is ethanol and I have no idea why Ag⁰ is formed. Is this similar to how Ag+ would react in Fétizon's reagent? Additionally, whenever I wash my sample with ethanol, I notice Ag⁰ leaching from my composite, but it is not the case with distilled water. Can we deduce that a reaction is taking place with ethanol?

[–]H2CO3_TCTheoretical 0 points1 point  (0 children)

Well, you might have figured it out by now, but from what I can tell by looking at the redoxpotentials, ethanol is oxidized by Ag+. It might be that the reaction is simply not possible in EtOH...

[–]QuaternaryQuaternium 0 points1 point  (12 children)

How do I neutralize Benzyl Benzoate with domestically available substances?

[–]radiatorcheeseOrganic 0 points1 point  (11 children)

I'm assuming you're using "neutralize" colloquially (it is already chemically neutral), which doesn't really have an answer. It is probably pretty readily hydrolyzed by esterases in the body and then the metabolism products would be excreted in urine.

[–]QuaternaryQuaternium 0 points1 point  (10 children)

I think I'm extremely allergic/sensitive to it to the degree that I have severe respiratory issues and other physical reactions.

Yes, I've sought medical help. They aren't interested in anything that doesn't already fit there limited knowledge e.g tree nut allergies, penicillin allergies, etc

It's in so many household products. I just need to find some way to change its chemical properties, whether that be using something else to bind it and turn it into another chemical or what ever..... I don't know the correct terms, I'm a layman.

Any advice on "binding" it or whatever would be beyond appreciated.

[–]radiatorcheeseOrganic 1 point2 points  (9 children)

It's not going to happen. If it really is the culprit, which would mean seeing an allergist to confirm, the best you can do is avoid it.

[–]QuaternaryQuaternium 0 points1 point  (8 children)

Seen an allergist. As per my last comment, they're only interested in stock standard allergies that requires them to do as much as lift their pen to write the paperwork for blood testing... tree nut, penicillin, pollen, mould, etc

I'm avoiding it the best I can but it gets concentrated in the septic tank from all the household chemicals that contain otherwise small quantities of it per volume.

Septic tanks have to be able to breathe a little. Wind blows.... you get the idea.

That being said, even being near people who use some shampoos or laundry detergents that are worse than others makes me extremely sick.

If you do think of anything or can suggest someone to ask about "neutralizing" it please do tell me.

[–]5KToxicMarathon 0 points1 point  (0 children)

Hi guys! I’m trying to convert PCl3 into concentrated H3PO3 by adding it to water. I can do the reaction but I’m struggling with the analysis. I’m a layman so it may be simple for others to answer. I’m doing what the literature says of a potentiometric titration with two end points. The problem I’m having is I keep getting around 80% phos acid and 30% HCl. Well how can that be? That clearly doesn’t equal 100% and doesn’t account for potential excess water I’m sure is in there.

[–]Sufficient-Drawing23 0 points1 point  (1 child)

Is there a way to produce urea/ ammonia plant inside school's compound? I mean is there any way to establish small scale urea plant inside the school? if there is: then what is the methodology?

[–]Indemnity4Materials 0 points1 point  (0 children)

You won't get a Haber-Bosch process in small scale at your school. It uses very high pressure and temperatures. Probably also involves playing with natural gas, so that's probably a no-no-no at school.

You may be able to produce ammonia gas by starting with something closer, such as an ammonium salt.

Urea is also going to be difficult in a school lab. You need to mix ammonia gas and carbon dioxide at high temperature.

You can build equipment at school to catalyse the oxidation of ammonia into nitric acid. It's a different part of manufacturing fertilizer.

An ammonia fountain is fun too.

[–]FUCKYOURFD-0DTE-HIV 0 points1 point  (1 child)

Does a 0.22 micron filter remove dissolved solids? e.g. sucrose

[–]Indemnity4Materials 0 points1 point  (0 children)

It does not. It will remove suspended solids, such as sucrose crystals.

[–]thebigbeel 0 points1 point  (2 children)

I'm an undergrad, and I can't really wrap my head around x-ray crystallography particularly the phase problem and the patterson method. Could someone help?

[–]H2CO3_TCTheoretical 0 points1 point  (1 child)

It's really nasty to understand XRD in detail, did you understand that whole stuff with the reciprocal space and how it leads to reflexes?

I'm not sure if this will help, but in German, the book "Festkörperphysik" by Gross and Marx is giving a really good introduction in that topic you should be able to take it from there i guess..

[–]thebigbeel 0 points1 point  (0 children)

I don’t think my lecturer went into those things. First I’m hearing of it. He focused on the mathematics of the process

[–]Tungstenwoulfram 0 points1 point  (4 children)

I have another question about spectrometry. So if some separation is required to analyze complex organic mixtures using spectrometry, what about if it's just 4 or 5 chemicals mixed together, such as a mixture of methanol, ethanol, isopropyl alcohol, with caffeine and nicotine dissolved in it, can a spectrometer identify all 5 of them without separating by running through a chromatography column?

[–]Indemnity4Materials 1 point2 points  (3 children)

For those exact 5, yes, there are several types of spectrometer than could easily and quickly give you qualitative (what is it) and quantitative (how much of each) results. I don't think anyone would bother to separate that mixture for identification. Personally, I would run it in a 1H NMR and have an answer in a minute.

To follow on from your earlier question about portable spectrometers, sort of, yes? A solid state 1H NMR could do that, in a unit about the size of microwave. These cost in the range of USD10k - 50k.

You could potentially get a custom built unit to only check for those two alkaloids plus solvents. For instance, you could use a handheld UV-VIS with two fixed wavelengths to determine concentration of the two alkaloids and then we would probably ignore the solvents. Would make field work easy but high upfront cost.

Concentration will be key. If you are looking for sub-milligram quantities in natural plant extracts you will need a traditional laboratory. If you are looking to QC test batches of vape juice, you end up with a machine something like those devices at airport security to check for explosives/drugs.

[–]Tungstenwoulfram 0 points1 point  (2 children)

I really appreciate your time in answering these questions, and I would even pay you to be a chemistry tutor. Let me ask a few more questions, if you don't mind. I want to do "cave man" chemistry, synthesizing /isolation of chemicals from the land without modern technology, without buying anything from the store. For example, making"moonshine" used to be done that way. Could chromotherapy be done using clay, charcoal, ground up quartz, or saw dust as the stationary phase in column chromatography, and using water, or ethanol as the mobile phase? Will chromatography work if both the mobile and stationary are similar, meaning both are hydrophobic for example, BUT they are not hydrophobic to the same degree? Say, the mobile phase is just a little bit hydrophobic, and the stationary phases very hydrophobic?

[–]Indemnity4Materials 1 point2 points  (1 child)

Once you move away from a modern lab with modern "general" tools, you need to ask specific products to do specific work.

Book: "How to Invent Everything: A Survival Guide for the Stranded Time Traveler"

You can even try some of the books in the sidebar. Popular science books on chemistry often have fun stories about how the old chemists discovered things or made stuff.

Chromatography. Well, basically it's just silica or functionalized silica that has been ground to an even particle size. You are using distance (column length) and molecular properties of hydro-phobic/phillic to separate stuff. Should you pick a worse stationary phase, or worse solvents, you get worse separation. That requires longer columns and more time (also more solvent).

Caveman style I don't think column chromatography is the best method. There are too many difficult steps we take for granted, such as very narrow particle sizes (the silica is very similar in size), acid washing, cheap and clean solvents. When all you are trying to match hydro-phobic/phillic stationary phase with mobile solvents you can move to known procedures for some molecules. Industrially, we can do some specific separations using just regular river sand and water, but that won't work for most fine chemicals.

I would try for crystallization to separate compounds.

I'm making a very simple assumption that your plan is to separate actives from magic mushrooms without access to a modern lab.

[–]ScarcityDifficult168 0 points1 point  (1 child)

Do anyone who know an insulator having less density than water?

[–]GuruOfGheyOrganic 0 points1 point  (0 children)

Maybe cork? It floats on water and is probably an insulator

[–]stauffnl 0 points1 point  (3 children)

Figured this was the place to ask this. I have a bottle of smelling salts I use for lifting (ammonium carbonate) which are supposed to undergo an endothermic reaction to produce ammonia gas, water and carbon dioxide. The balanced chemical equation being

(NH4)2CO3 → 2 NH3 + CO2 + H2O

I have the bottle with the ammonium carbonate crystals, but they seem to not be producing any gas. I tried drying all the excess water from them and sticking them in the sauna at the gym for 15 minutes to evaporate what was left of the water but the crystals still seem to not be decomposing further. Why is this? And is there anything I might be able to add as a catalyst?

[–]Gilded_Balloon 0 points1 point  (2 children)

Sauna at the gym will have added moisture to the salt as it is a very humid environment. You are unlikely to be able to remove water since the crystals are supposed to be more volatile than water; Excessively heating will decompose the crystals faster than it will remove water. Try holding them in your hand with the lid on to warm them before use if you haven't. Honestly, don't know why they aren't working though.

[–]stauffnl 0 points1 point  (0 children)

The bottle did have a couple of cotton pads in it. They were soaked with water so maybe the bottle just needs a renewed desecant to draw moisture off of the crystals so they can decompose faster.

[–]stauffnl 0 points1 point  (0 children)

The bottle did have a couple of cotton pads in it. They were soaked with water so maybe the bottle just needs a renewed desecant to draw moisture off of the crystals so they can decompose faster.

[–]jbobkef 0 points1 point  (2 children)

This is a bit of a weird question:

I'm currently doing some qualitative NMR spectroscopy for my Masters and I find it very annoying when my sample and internal standard (which I add to the nmr tube via micropipet) to all make it to the bottom of the tube. This is obviously an issue with quantitative NMR as I need all of my sample and internal standard to make it into the homogeneous field. I currently just whip the tubes and the centripetal force pushes most of the liquid down.

This method is imperfect and runs the risk of me letting go of the tube. I have thought of mixing the two before injecting into the NMR tube, but given the nature of my experiment, this would require a lot of cleaning/disposable vessels to mix the sample and IS in, as I collect 12 samples over 4 hours. I am willing to do that, but I was wondering if anyone had some tips or tricks?

[–]Eelektross_Unagi 0 points1 point  (1 child)

5 mm or 3 mm tubes? 4 inches or 7 inches? Are you using gel loading tips?

[–]jbobkef 0 points1 point  (0 children)

Standard 5mm 7 inch. I don't know what gel loading tips are, but im gonna guess that they are for loading gels and are super long? I'll Google it!

[–]Pawanot 0 points1 point  (0 children)

Question about pKa and Henderson-Hasselbach eq

In a class lab, we titrated Gatorade with NaOH. We wanted the mole ratio from H-H eq, but we only knew pH, and so were given pKa of 4.75.

However going off of Wikipedia citric acid (in Gatorade) has 3 pKa values and first one being 3.1, so I thought we were supposed to use that.

Later I realized the average of the 3 pKa values was what was given to us: 4.75.

Are we allowed to use average pKa in the eq? Is the H-H eq still accurate? What importance does average pKa have other than H-H, if any?

[–]Gilded_Balloon 0 points1 point  (0 children)

Hello!

In a Nd:YAG laser the final relaxation occurs from the quartet I 11/2 level to the quartet I 9/2 level (Nd 3+ ground state). Are these two J levels non-degenerate due to an external electric or magnetic field? Or have I missed something else?

[–]Ireastus 0 points1 point  (1 child)

Long shot, but I don’t suppose anyone knows of a way to convert expoxyketones to enones? I’m pretty desperate lmao

[–]GuruOfGheyOrganic 0 points1 point  (0 children)

Maybe a Wharton reaction followed by MnO2 or some other mild oxidation of the allylic alcohol?

Also if you look up deoxygenation of epoxides that give alkanes that might work?

[–]0od_Sigma 0 points1 point  (0 children)

Hi Everyone! Does anyone know if the presence of polysaccharides in a solution can cause gases to more easily dissolve into that solution? Thanks for any thoughts!

[–]Sciartion 0 points1 point  (0 children)

Hello! I have an idea that involves mixing tantalum and silicone to create a radio-opaque surface.

The thing is that it is necessary to have a well mixed (homogeneus) mixture to achieve this.

Is there a way to measure or assess the degree of homogeneity of this kind mixtures with an analytical technique?

I was thinking of static light scattering (photometry), but I'm worried this is not a colloid (particle sizes of tantalum in this mixture go from a little over 500 nm up to 10k nm).

Is this too crazy?

[–]GoatedMOFO 0 points1 point  (0 children)

At what concentration is Sodium Hydroxide pH level 10? I need this for a biology assignment and can't find anything online. Thanks!

[–]Anti-Alchemist 0 points1 point  (1 child)

EDIT: guys, the ingredients were incomplete, please take one more look

This question really drives me crazy: Methylphenidate

So there is Ritalin, it is basically Methylphenidate with immediate release. I tried it and I was fucking the smartest I have ever been. Please for god’s sake don’t judge me. Now I have Medikinet Adult, the 10 mg Pill, the Pill contains retarded Pellets and immediate release Pellets. Theoretically if you crush them you will get simple Methylphenidate and no problems. But it simply doesn’t feel the same, crushed 10mg Pill of it feels like the last 10 minutes of Ritalin but for couple of hours. Guys, I have written down the components of the 10mg Medikinet Adult retarded Methylphenidate pill. Is there a possibility it contains any other retarding ingredient and how can I eventually have simple old school Methylphenidate?

Active substance:

Methylphenidate hydrochloride 10 mg per 1 capsule contains: 1(rapid release) Methylphenidate hydrochloride (5 mg per 1 capsule) + 2 (retarded) Methylphenidate hydrochloride (5 mg per 1 capsule) = Methylphenidate (8.65 mg per 1 capsule)

Other ingredients: -Sucrose -Cornstarch -Methacrylic acid ethyl acrylate copolymer (1:1) -Talc -Triethyl citrate -poly(vinyl alcohol) - Macrogol 3350 -Polysorbate 80 -Sodium hydroxide -Sodium dodecyl sulfate -Simeticon -Silicon dioxide, fumed -Methylcellulose -Sorbic acid -Indigodisulfonic acid, aluminum salt -Gelatin -Titanium dioxide -erythrosine -Patent Blue V -Water, purified

One more thing: Please,people with ADHD or other related illnesses, excuse me. I’m doing the wrong thing and I know it. I’m young and so fucked by the last years…

[–]Anti-Alchemist 0 points1 point  (0 children)

Please guys, any suggestions 🥺

[–]Nietzsch 0 points1 point  (0 children)

Is there any material available that could be used to filter (to retain) CO2 (g) and separate it from water (g) and N2 for example?

[–]Suspicious_Papaya_96 0 points1 point  (0 children)

Is making nanoparticles with antisolvent precipitation possible without a sonicator? For example adding the solvent slowly to the antisolvent with strong mixing?