Hello. Are there any websites, YouTube channels, or other resources to practice multiple-choice questions, matching, etc., for first-year chemistry? I want to quiz myself on theory and some math that doesn't require solving and can be done easily by looking at the formulas, like when something is inversely proportional to something else, so that will be low, and then solving the problem with shortcuts and tricks. For example, chapters like ideal gases, quantum mechanics of the atom, etc. Idk if that makes sense.

Hi, I hope this subreddit is suitable for this question, can't find one that seems more suited than this.

I've got silica gel packets with some coloured beads that even show if one is saturated or not, but after asking the AI out of curiosity I am now at odds. It gave some clearly wrong answers because I already dried a pair once with my air frier and it took far less, but also said that the packets can release dangerous chemicals and so not to dry them somewhere I also cook food into.

So... what can I do? probably dumb question, but is it safe to put ONLY the packets in to dry them, and then after cook food? Possibly after several hours have passed and I leave it open so that any chemical gets out... unless it is depositated, again, I have no idea. Another option that comes to mind would be, if they can be dried in the microwave (or ia it too aggressive?), put them inside a smaller container that is sealed so that any chemical released doesn't contaminate the microwave.

Yeah, just some thoughts but I don't have any idea how sound they are. Hope to get some advice, would be much appreciated. Thank you 🙏

Perdon si este no es el foto adecuado, es que no se que mejor que un quimico para un consejo de estos; pero, Ya realice el truco de pasarle un marcador borrable encima, alcohol de grado medicinal (estoy en trabajo de campo y me quede sin isopropílico) y otros trucos, pero pese a que el pigmento se aclaro bastante, aun hay manchas... quisiera saber que puedo hacer para eliminarlas completamente... ya que me encontraba realizando unos calculos y me quede sin espacio en la pizarra y por error estuve usando un marcador permanente por bastante tiempo, hasta que lo noté... algun consejo sobre como puedo diluir la tinta seca en el material?

I promise I'm not a terrorist, I'm just writing a story 😅

So basically for plot reasons some characters have to blow up a dam and do so with something that won't leave relevant traces of itself and possibly is a chemical agent not specifically designed as a bomb (one of them is the owner of a chemical company so she'd have little trouble acquiring chemical agents, but proper bomb components would be super hard to get without arising too much suspicion).

So I thought of anhydride sodium bc it reacts violently with water and unlike a lot of other explosives, its explosive reactions should be enhaanced intead of slowed by it. Plus Na+ ions are rather common in water, so it would be hard for people trying to find the culprits to understand what they used in the first place.

The sodium would be dropped in one or a few sealed boxes from basically a plane flying over the dam with a small device/mechanical component that causes them to open once they're already in the water.

The question is, would it work? How much sodium would they need to use? (They're not trying to destroy the whole structure, just to create a large enough breach that the dam is no longer of use).

Thank you!

Hi everyone, I have a question for those working with food analysis.

I’m analyzing iron in fortified wheat flour, and I’m wondering which sample preparation method you usually use: microwave digestion with HNO₃/H₂O₂ or dry ashing before analysis by AAS or ICP-OES.

I tried dry ashing at 450°C for 12 hours, but the flour still has black particles and doesn’t turn into proper ash.

Has anyone experienced this before? If you use dry ashing, what temperature and time do you normally use?

Also, have you ever compared the results obtained by dry ashing and microwave digestion? Which method gives you better iron recovery?

I’d appreciate hearing about your actual lab experience. Thanks!

Some time ago, I created two quiz courses on QuizAcademy for our students covering instrumental (bio)analytics, with a main focus on NMR spectroscopy and MS spectrometry.

Since my English is unfortunately quite poor, I decided to translate these quizzes from German into English with the help of AI. Now my request: If anyone here has the time, inclination, and/or interest to take a look, I would really appreciate any feedback or spotted errors.

Thank you!

Basic Course

https://quizacademy.io/U-COJYYR

Master Course

https://quizacademy.io/U-CIDYNN

The use should be possible anonymously. I cannot draw any conclusions about users. In addition, the operator should work in accordance with the European GDPR.

Many thanks

ps: I am just an employee and do not have the means to pay students for this activity. However, I would like to make the quizzes available to the general public.

So I set up my reaction with 80ml DMF, and after completing the reaction (starting material consumed as monitored TLC), the procedure stated to filter the reaction mixture and wash the solid with h20, i tried to filter it and started washing with h20, but none persisted on the filter paper on buchner funnel and almost all went to filtrate, perhaps it wasn’t pure on TLC, hence not solidyfying.

Now I have a miscible mixture of DMF and water , I added nearly 200ml water. I tried extracting with chcl3 since my product is readily soluble in that but I am not observing layer separation on the extraction funnel.

Now I have a miscible mixture of dmf water and chcl3, whats the best course to get my product?

I intend to do column after this to isolate the red spot at the top (in 2nd lane) which is my target compound. Please ignore my novice english.

I found this interesting piece of schlenkware in a drawer in a now defunct lab who was at this university for many decades. I’m very intrigued what the purpose is, since the j young tap opens the flask to gas and to air. My thought was that the left side arm was for reagent addition, but then it’s impossible to keep it under positive pressure while not adding reagents? I guess you could cover that side arm… My boss is an experienced air free chemist, and he was also not sure. Perhaps it’s for storage of dry solvents? Has some similarities to the bombs we use for that in my lab.

Ask the r/chemistry intelligentsia your research/technical questions. This is a great way to reach out to a broad chemistry network about anything you are curious about or need insight with and for professionals who want to help with topics that they are knowledgeable about.

So if you have any questions about reactions not working, optimization of yields or anything else concerning your current (or future) research, this is the place to leave your comment.

If you see similar topics of people around r/chemistry please direct them to this weekly thread where they hopefully get the help that they are looking for.

Just a random question I thought about but while there always standard safety protocols in a lab I was just curious as to what is a habit that bother or annoys you in a lab. Not to shame anyone or anything just curious
Edit: can’t get to every comment but thank you all for the replies:)

Hi all. I've just noticed that most catalytic reactions that I've encountered mainly involve organic products and reactants. Inorganic catalysts can be used in these reactions, but there are only a few catalytic reactions where the reactants and products are mainly inorganic. I wonder if this is just because we haven't discovered as much inorganic catalytic reactions or there is something in nature that lead to this.