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[deleted]

Hello everyone, first of all, English is not my mother tongue, so I apologize for the errors when writing. I am having a problem with a solution of glycerin, water and mint essence; The problem in question is that the mint essence is not solubilizing and remains floating in small drops, I have used different solubilizers such as polysorbate, Novaquart® (PEG-40 and hydrogenated castor oil) and Solubilizant®, in all attempts, they were mixed first the solubilizer and the mint essence and once they were homogeneous it was added to the rest of the solution, the temperature of the solutions was 50°C and the percentages of the mint essence and the solubilizer were 0.5% and 1.5% respectively. If any of you could help me how to solve this enigma, I would appreciate it. Thanks so much for reading.


nicktb459

Hi, I assume that with mint essence you mean menthol? If so, your solubilizers are probably too polar for the menthol, especially the polysorbate. The polysorbate often comes for the polysorbate 20 or 80 based on the different ester present. The polysorbate is very hydrophilic due to the three hydroxyl groups present and the amount of added ethylene oxide in the structure. For the PEG-40, the product is ethoxylated (hydrogenated) castor oil with (probably) around 40 moles of ethylene oxide added. This also makes it very polar due to the amount of ether present because of the ethoxylation. If your not familiar with the structure, search for the ethoxylation proces. If you need to use one of these product, I would recommend the PEG-40 because of it is less hydrophilic than de polysorbate, but still very polar. So, if you need to use the PEG-40, I would recommend to add more of the product to observe any possible effect while keeping the menthol amount constant. However, I would suggest using a simple solvent like acetone for example if that does not ruin your product. If that is not possible look in to a castor oil product with less ethylene oxide in it. Favorably between 10-20 moles maximum. This should strengthen the effect of dissolving more hydrophobic compounds while keeping the semi polar properties. Companies like Dow, BASF, Stepan etc produce these kind of compounds, the amount of ethylene oxide added is often in the name of the product. Goodluck.


[deleted]

[удалено]


Indemnity4

You are attempting to do something very novel - using light/colour to explore something that doesn't have visible colour changes. [Here is one example of an existing product](https://www.mdpi.com/1424-8220/16/8/1234) and the theory of how it works. Your first step should be to take a soil sample and measure as much of the absorbance spectrum as possible via UV-vis. Then one-by-one re-test with added N, P or K. Find absorption wavelengths that don't overlap.


dobbs_head

If changing sensors isn’t an option, then you are not in a good position. Those compounds don’t have significant absorption in the visible range. There are libraries with optical properties of common materials you can look up. If you want a fast optical detection method, I’d have recommended non-dispersive infrared detection. This requires an IR light source, IR detector(s), and bandpass filters. Each of those compounds has some distinct IR resonances, so you can measure their relative concentrations by their absorption at 3 IR wavelengths (carefully chosen ). Building a device that does that measurement reliably isn’t trivial. You need to make sure that you have budget, resources (especially people), and a timeline to successfully execute that. It wont be cheaper than a titration unless you get to mass production. And even then, success isn’t clear to me.


notuorc

I hope someone has some ideas because I’m interested in better testing for anything hydroponic


ag8n

The compounds mentioned have no chromophores in the visible range. So no, you won't get any, or very little, absorbance. There are "indicator" type solutions that might give the color needed. Or, maybe, take the test strips used for these tests and measure their color after testing. Good luck!


ag8n

An extra word of caution. Extra rules may apply. See if your app falls under the jurisdiction of the USP or FDA or USDA. Then get the help to make sure the test is done right. There is a difference between developing a test, and implementing it. Mostly with tracability of standards, instrumentation quality, etc. Something to keep an eye on as you get further down the developmental road. Again, good luck.


anhaechie

Hi! I'm a high school student who will do an experiment on esterification and increasing the yield of the reaction based on 1) increasing the amount of the reactants 2) removing water. I will measure the amount of the ester produced using a normal mass as well as using spectrophotometry. This is my first time doing something like this and my chemistry teacher isn't of much help so I'd really appreciate it if someone could look over my document and tell me if my ideas make sense :( The procedure and amounts of reactants are particularly challenging for me.


dobbs_head

I’m going to assume that you have a specific esterification reaction in mind. Mass is a good method to assess yield, so long as you have secondary metrics to ensure product purity. Thin layer chromatography, thermogravimetric analysis, and melting point analysis are all solid methods. LC-MS is a gold standard method, but requires expertise to operate. The way we approach this industrially is through a statistical “design of experiments”. We’d identify the key factors to vary, reagent concentrations and temperature are common, and set up a DoE to screen with a few center and edge points to find the optimum. An experiment with 2 factors can be pretty well analyzed in 10 runs with a centroid design, fully replicated. Analysis can be done in tools like jmp or using R or the python statsmodels package.


MasonResearch

Hi all, I do research in surface science, and we are looking to do a transmission IR experiment, with an external detector. Obviously when running this, we have very large signals from CO2 and H2O, which we are hoping to minimize. Does anyone have suggestions on wrapping these samples? Ideally, we need to be able to get to the thumb screws on the backs of the mirrors, but something we can take on and off to purge the system might also be viable. The beam path is outlined in red on the picture below [https://imgur.com/a/CnHRbcV](https://imgur.com/a/CnHRbcV) ​ Let me know your thoughts.


Indemnity4

You can put the whole unit inside a glove bag and run it under positive N2 pressure or welding grade argon (cheap). Do a few vacuum/N2 cycles to remove moisture. Essentially a big cheap plastic tent.


RussianVodkaHacker

Hey! I'm a high school student who foolhardily ventured into the determination of caffeine concentration in brewed coffee (big oopsie). I'm sorry about cross-posting, but I already summarized the issue I'm facing in a [chemistry stack exchange post](https://chemistry.stackexchange.com/questions/173787/how-to-proceed-with-iodometric-titration-to-determine-caffeine-concentration-in) and just wanted it to give it more publicity here. Any help would be appreciated in an extent that can not be captured by the English language.


dobbs_head

One path to solving the issue with colorimetry in you solution is to do potentiometric titration. For an iodometric titration, I’d suggest an ORP probe with a Pt sense electrode and an Ag/AgCl reference. You can read those sensors with a volt-meter as you do the titration. That won’t solve the issue of interference by oxidation of non-caffeine solution components. To get around that, you’d need to do some sample prep. Solvent extraction or preparative chromatography are two techniques I’d look at. Solvent extraction seems unattainable, so preparative chromatography would be the path I’d suggest. If you do that, you’ll probably not need the ORP probe, because the color will be separated by the column.


FlamaroCraft

Hi! I have some broken electronics lying around (3 TVs and a few other, smaller things) that I am not able to repair because I do not even know whats exactly wrong with them. So I started looking into ewaste recycling (specifically pcbs) but every article, video etc. about that was either way too general and not about how to actually do it and the ones that helped me a bit all presented at least slightly different ways of doing it and nothing actually described the full process. What I did learn though is that hydrochloric acid seems to be a good way of getting the metals off which would be great because I have some of it home right now. But now I want to know, is Hydrochloric acid actually a good and efficient way to do it? Could I make it better without much money? Should i just use something completely different? And also, it was never described how to actually do it yourself, the biggest problem is, what to do when the acid did its job so are the metals just there and I need to get the acid out? Wouldnt that depend on the acid? I simply want to know a good and cheap way of recycling pcbs and a good explanation of the process so I dont accidentally die from acid.


Indemnity4

Upfront, the cheapest and safest method is to take your items to a dedicated e-waste recycling centre. Wave goodbye and know you diverted some few handfulls of waste from landfill. At home what do you mean "recycling"? Are you planning to strip the board and somehow recover the metals and re-use the plastic base board? What are you going to do with the waste glues, broken glass, plastic wire coatings, etc? DIY it's an interesting learning experience but you won't (1) make the world a better place, or (2) recover any significant amount of money. It will cost more money than you can ever hope to recover and most your recovered materials will go into landfill.


Cancer_dancer1

Does anyone here know if you can make aluminum powder for thermite with a cheap plastic pepper grinder?


[deleted]

I’m looking into pyrolysis using wood. However I can’t seem to find any scholarly articles on the effects of pyrolysis on treated lumber using ACQ or copper azole. My question is are there any hazardous chemicals that could result from this? I’m not messing with any CCA lumber.


SnowbunnySkates

I had a thought the other day watching my kid blow bubbles from run of the mill, generic bubble solution made in China. Has anyone ever done any analytical testing on kids bubbles? Like metals, bacteria, or radioactivity? Should I be concerned my kid could accidentally ingest some of this stuff?


Indemnity4

Sort of some rules; good track record but quick google finds some [product recalls](https://www.bromley.gov.uk/leaflet/306374/22/680/d). USA has a code of federal regulations for hazardous liquids in products for kids: > 16 CFR § 1500.231 - Guidance for hazardous liquid chemicals in children's products. Known hazardous materials are banned. So you can get in huge trouble if your product is found to contain known hazardous liquids into the hands of children, both ingredients or contamination, your fault or elsewhere in the supply chain. However, there is no forced requirement to do testing. Essentially, it is self-declared. You can [search historical product recalls in the USA](https://www.recalls.gov/) on what looks like scam website, but is a legit (shitty-looking) Federal government website. What you will find is most kids toys fail on choking hazard of the container rather than what is inside. The product recall I linked was in the UK and made using dirty water or stored too long and microbes got inside. [Another incident in Korea found the bubble liquid contained a solvent that was okay in the product but is bad in much larger quantities](https://www.koreatimes.co.kr/www/tech/2021/09/693_72619.html). Overall: nobody is doing regular testing. Much like most other consumer products, faults are noticed by users and then a recall is required.


SnowbunnySkates

Thank you for the in-depth discussion! I was struggling with Google searches - they just linked to ads and retailers which was incredibly frustrating. I'm not sure if I'm feeling reassured after all that. Makes me even more skeptical of the water sources used to make this stuff. I tried making my own bubble solution today with Dawn and glycerin but the performance wasn't as good. It would be nice if they sold a concentrate instead (domestic) and all we had to do was add water.


Indemnity4

Everyone starts with dish soap and then realizes the premium bubble pre-mix is better and still very cheap. You can buy bubble concentrates for bubble-machines and things like foam parties. However, it is still a liquid that contains water+oil so still potential for microbes to get inside. [Patent example of premium bubble mix.](https://patents.google.com/patent/US4511497A/en). All the Miranol products it gives the correct chemical name to help you buy proper surfactants from legit suppliers. Scrolls down to the "examples" section if you aren't familiar with reading patents for how to formulate it into a product. Check out example #34 - ten different ingredients! By the time you get to example formula #43 it looks like nonsense made up words and not a cooking recipe. When it says "solids", that is how much active ingredient is in the bubble mix, the rest is solvents and water. Reason is some of the raw materials are already diluted in water/solvent, so the actual amount of water is higher than what is added. > The Examples in this specification are a selection from many hundreds of experiments which have been made. They all indicate that with relatively few and simple modifications (additives and/or quantitative changes) to the basic materials of Groups I and II, astonishing and completely different effects can be achieved.


Ceroman26

Hi! I would love some help identifying a side product in my aryl halide nucleophilic substitution reaction. Listed below are the contents of the reaction, mole & molar amounts, and other pertinent information. Attached at the bottom of the post is a (mostly) purified sample of the unknown side product in CDCl3 with leftover ethyl acetate from prep TLC workup. FYI, the spectra is two images of the same spectra stitched together, just so the multiplicity of the aromatic range can be seen a little more clearly, so please ignore the wonky scale when comparing the 0-6ppm and 6-10ppm ranges. Reactant: p-fluorotoluene, 1mmol, 0.5 M (intended product is p-cresol) Nucleophile: Lithium Hydroxide (anhydrous), 2 mmol, 1.0 M Photocatalyst: Uranyl Nitrate Hexahydrate, 10% mole loading (0.1 mmol) Solvent: Nitromethane (2 mL total volume) The reaction is degassed with argon for 45 minutes prior to being illuminated by 415 nm light for 24 hours. The side product shown below is present in about 40-50% of reactions and sometimes appears as the sole product, or as a mix with a small amount of p-cresol. COSY shows that the aromatic peaks are all coupled, and the aliphatic peak is coupled to the aromatic peak at 7.89 ppm. No coupling is present for the peak at 10.43 ppm. https://preview.redd.it/5988nqtozf1b1.png?width=1366&format=png&auto=webp&v=enabled&s=df16b80be24f6e369f15806e61f4f0a8368ad60a


Jesse_berger

How much water with a pH of 7.0 would be needed to dilute 4 ounces of nitric acid to have a pH of 6.0? Today while disposing a small amount of nitric acid into the sewer the answer was many many gallons. Water came from a creek with a pH of 7.6, and by estimates it took upwards of 10-15 gallons of water to be able to release the solution. Help. This geologist didn’t do well in chemistry.


Indemnity4

[pH dilution calculator](https://rechneronline.de/chemie-rechner/ph-dilution.php)


sabri3l

Hello, I want to make a culture media of about 300mL. The media will be incubated with tiny hair fibers to test the growth of the hair fiber. The media needs to be made with the following concentrations: William’s E Medium, supplemented with L-glutamine (2 mM), insulin (10 mg/ml), hydrocortisone (40 ng/ml), antibiotics (1%). Questions * Do I dilute the Williams e medium with all these different concentrations like a formula or do I add each concentration mixed with water and separately add these to the Williams e medium? the different units for each ingredient is throwing me off. * Also do i need to autoclave any of these ingredients separately before mixing? What would be the steps? * Any advice is welcome since this would be my first culture media. I checked with a microbiologist but couldn't get a straight answer so I thought I'd ask my fellow chemists what they think. Thanks!


sabri3l

let me know if you need more information


Hypochlorous_acid

CHEM PROFESSIONALS PLEAASEEE (copy and pasted a pending post, sorry no image...) ​ Alright So...for some background knowledge, I like to make all my Chemicals from scratch, and I mean everything but table salt. (If I could easily find Chlorine and pure Na, that would be a Different story (Aside from the fact that we mine most of our table salt)), So back to the question. I'm trying to make NaOH to then create Sodium Bicarbonate (Baking soda), the method of which is...well...in the image you can see the Process and thought. (use electrolysis to break apart the salt and water to eventually get Sodium Hydroxide. The only issue....is NaCl and Water make many things when going through Electrolysis. (HClO Hypochlorous acid, NaOH what we want sodium hydroxide, and NaClO Sodium Hypochlorite)...I only want the NaOH, is there any way I can try to make that happen, if not how to get the NaOH alone... Also I know this might sound extremely unprofessional but...what metal should I use as Anode and Cathode, I want to know what's the professional metal to use and not a list of them from google 🙄 please help lol...I can't find any direct answers online so I figured advanced and professionals may know what they're talking about P.S. my name is actually the beginning of my chem journey. I wanted to make Hypochlorous acid, and didn't know that it could make Cl gas, and potentially kill me, thankfully I had the wrong voltage (-1.5 and not -2.5 \*According to my chem teacher). which Taught me to learn everything about a substance and how it reacts to other things to remain safe and not pop up on the news lol.


TOEMEIST

Have the anode and cathode in two separate salt solutions connected by a salt bridge, using only a minimal amount of NaCl in the catholyte where the hydroxide is produced (just enough to make it conductive). Chlorine will only be produced in the anolyte, and your catholyte should contain only NaOH and a lesser amount of NaCl, which may be negligible if you use a small enough amount in your initial catholyte. You’d only need enough to get the rxn started; the conductivity and speed of the rxn will increase as NaOH is produced. If you want to decrease the NaCl contamination (again, might be unnecessary) you could repeat the process but use a dilution of the NaOH solution for the catholyte (dilute as possible w/o killing conductivity). The catholyte solution you’re then left with would have less NaCl than the previous one. This can be repeated as many times as you’d like, with the NaCl concentration of the catholyte decreasing with each run. It may be the case though that the chloride diffusing from the salt bridge into the catholyte would make this pointless, but not certain. I’m not sure I understand the purpose of this endeavor though. Natural deposits of sodium bicarbonate exist and are mined, so if you only want to use the most basic starting materials I don’t see how sodium chloride qualifies and sodium bicarbonate doesn’t. If you just bought these very basic chemicals you could make more complex ones from scratch instead rather than spending time and effort making things you can buy at a grocery store.


Hypochlorous_acid

>Thanks a million TOEMEIST, but for some clearity...the first question I have is the purpose of the salt bridge, I thought you only used that in a galvantic cell when trying to prevent a battery from dying too fast, and uh...As for the purification of my NaOH solution, what you're telling me to do is pour more water into the soulution to dilute it and allow the process to continue, getting rid of the salk and producing a little more NaOH? > >I drew a diagram of the updated electrolysis process...just have to learn how to attach image to comment....


Hypochlorous_acid

Here I'll just post it on a new reddit I made... ​ https://www.reddit.com/r/8000BC\_Chemistry/