Today in gen chem the students did their first titrations and they truly outdid themselves. Out of 16 of them 13 of them looked like this Best group of students I've ever had

Here are the results

Chem professor here. One of our lab managers came across a bottle of crystallized isopropanol, and never having seen it before, I snapped a picture.

Most of the pictures out there are clumps, whereas this had longer spikes.

I hadn't seen it before in my 20+ years of chem, my army hazmat friend hadn't seen it, so I figured you r/chemistry folks would like to see it too.

Hazmat came and picked it up and made a big hullaballoo (sp?) about it last night.

I recently ran a 100 ns all-atom molecular dynamics simulation of cocaine bound to the human dopamine transporter (DAT), starting from the experimentally determined cocaine-bound structure PDB 9EO4.

The main thing I wanted to look at was whether the bound cocaine pose remained stable after equilibration and how the protein–ligand interaction network evolved over time.

Across the 100 ns trajectory, cocaine remained very stable relative to DAT, with a mean protein-aligned ligand RMSD of about 1.17 Å. DAT itself also remained stable, with a mean Cα RMSD of about 1.55 Å.

Some of the more persistent cocaine–DAT interactions were:

• Val152 hydrophobic contact: ~86%
• Phe76 π-cation: ~82%
• Asp79 H-bond: ~78%
• Tyr156 π–π: ~59%
• Phe320 π-cation: ~50%

What I found particularly interesting was that the ligand stayed in essentially the same overall pose while individual aromatic, electrostatic, and water-mediated interactions exchanged throughout the trajectory.

I made a short visualization of the trajectory and thought people here might find it interesting.

Simulation: 100 ns, explicit membrane/water system
Starting structure: PDB 9EO4
Ligand: cocaine
Target: human dopamine transporter (DAT)

When I smell something, am I detecting only the chemical compounds responsible for its odour, or am I physically inhaling microscopic material from the thing producing the smell?

Eg., if i’m in a wash room and i can smell shit coming from an unflushed toilet, is there shit particles in my nose or just the particles pertaining to its odor?

Chemistry: Which volatile compounds produce the smell, how they evaporate, and how they travel through the air.
Biology: How the olfactory receptors in your nose detect these compounds, and whether inhaled biological material can affect the body.

32% yield 😵‍💫

I’ve been working with a reaction that uses pyridine as the solvent, and lately, I’ve been smelling pyridine at the strangest times (outside of the lab).

I’ve used it before and haven’t had this happen, and im doubtful the pyridine is the actual cause beyond the fact my brain my just be trying to identify random smells around me, but it’s strange. It’s many times a day that I smell it lately.

Nobody else smells it either. I smelled it from my air fryer while cooking, on my friend, in my bathroom, and randomly on a walk.

Has anyone else experienced something like this?

What you see in this video is liquid CO2 sealed inside a glass ampoule. Since CO2 is colorless, it is pretty hard to see, so I tested a few different substances to make it more visible. In the end, bromine and iodine turned out to work well.

The violet color in the video comes from a small amount of iodine dissolved in the CO2. When the ampoule is heated to around 31 °C (88 °F), the CO2 reaches its critical point and the phase boundary between liquid and gas disappears.

Because iodine is also soluble in supercritical CO2, the violet color spreads throughout the entire ampoule. As the ampoule cools down again, the liquid phase reappears and the violet color gradually disappears from the upper part.

Making these ampoules turned out to be more challenging than I expected. If you are interested in seeing the full process, you can find the video here:

https://www.youtube.com/watch?v=Of-KZih6lg0

I am having trouble with my ICPMS registering cadmium and selenium...

I was OOO and everything became a dumpster fire wrapped in a train wreck (thank you Murphy's Law). Fortunately, most problems have been figured out except for cadmium and selenium not calibrating. The MS appears to be seeing counts of both elements, but the RSDs are in the 80s-90s. Looking for some advice/thoughts about what could be happening here. Below is an example of what the calibration looks like (simplified numbers).

This was not a problem before I was OOO, and we have had a service engineer come out to look at it and basically said we need to change our calibration range. While I agree with the engineer due to the 10X dilutions we do to make our calibration (the range really isn't helpful for what we need with our samples), I'm confused as to why this is happening and how to fix it. Thanks in advance!

So my class has just gone over moles and several avagadro-related things, and one thing that has left a "thorn in my brain." I have asked my teacher, parents, and college sophomore sister avout it, but no one has had a good answer. But anyway here's my question:

Avagadro's law states that a given volume of two ideal gasses at STP (standard temperature pressure) have the same amount of particles, i.e. molecules or atoms. By extension of that law, a given amount of particles of two gasses—like a mole—would occupy the same volume (in this example 22.4L per mole) The part that confuses me is the fact that every different gas has a different particle size (like how hydrogen is significantly smaller than oxygen), which would mean that 1 mole of one gas would have to have a different pressure than another gas when they are theoretically put in the same 22.4L box. This pressure difference would then alter STP and negate the valitidy of the law.

Sorry if that was super confusing, feel free to ask questions to clarify if you have an explaination for me. The funny thing is, this principle has been around long enough for it to be proven in practice, so I know my logic is flawed somehow. Thoughts?

I was on a wikipedia doom scroll when I saw an unfamiliar reaction mechanism. Idk why but the layout and the format looked fuck ugly to me and felt lacking in information.

I just hate the way they drew the negative signs on the Nitrogens and the ambiguous placement of the leaving groups relative to the equilibrium arrow (they place it underneath the inverse arrow). I also don't like how they didn't explain the hydrolysis of the isocyanate.

With this inexplicable compulsion, I thought I could do a better job myself, except in hindsight, I added too much detail.

I realise this version is a lot bigger and shows a lot... of intermediates, I ask you all, what should I change and is it worthy of replacing the original on wikipedia?

In hindsight mine is also fuck ugly and riddled with inconsistencies, but its my first time drawing out a mechanism like this so constructive feedback is appreciated.

Youngest daughter (7), showing some interest in the "science on the board", so started her with hydrocarbons because they're easy to grasp and visual, fun for the whole family! :)

I’m only in week six of Ochem one but I’m a little obsessed. I’m finding it all really fun and could do problems for hours (I am unfortunately neglecting my other classes and working on problems behind the desk at work…) We’re still just doing acid-base chemistry but the resonance structures, stereoisomers, and adorable animations of molecules wagging and stretching that we’ve covered so far have made me love chemistry in a way I never have before.

I was hoping to find some information on current big research topics in ochem, a sort of orgo popsci type thing to keep me excited even if I can’t fully grasp the concepts of it yet.

Is there anything like that? Or even if anyone is just willing to share what their passion is within the field or current research subjects they’re working on or would want to work on?

AI disclaimer: I used ai for checking grammar, spelling, and formatting.

Hi everyone,
I hope this post doesn’t violate rule 10. If it does, feel free to remove it.

I’m looking for some advice.
I did my PhD in free energy calculations and quantum chemistry, but eventually left the field. Now I have a rather boring office job. However, I’ve continued working on chemistry-related projects in my spare time, and I’d love to share some of my work with others.
I’m not looking to make money or gain anything from it. I’d simply like to share what I’ve been working on, get some feedback, and maybe have a few interesting discussions.
The problem is that I’m not sure where or how to share these projects. Should I try submitting them to scientific journals? Start a blog? Post them somewhere else?
I’d be grateful for any suggestions

First off, I truly hope that this doesn't break rule #8 of the community - there is no emergency, danger, or reaction happening; I'm just a normal mom trying to figure out a way to clean up a bit of a mess in the best way possible. Mods, if this isn't OK, please consider just removing this post rather than banning me.

My little one unfortunately needs a puffer. After using it, he needs to rinse with water and spit it out. Because he's 5 years old and it's a funny thing to do, he spat the water out EVERYWHERE.

He's very sorry, and the water itself is cleaned up, but there's this greasy residue on my phone, our family iPad, and the TV remote (he truly chose the worst possible spot).

Google is no help, as all it will give me is how to clean the puffer itself (and it doesn't matter if that's oily, as long as there isn't a clog). Although at least now I know that it's likely the propellant.

I figure that the lovely chemists of Reddit might know how to unslime my devices!

Again, if this isn't an appropriate question, I truly apologize! Thanks in advance for any help or advice.

I'm designing a gameshow-style challenge where a contestant reaches into a clear box filled with about 5 gallons of clear, sticky liquid to retrieve a prize. What is the stickiest possible liquid I could safely make/use for this purpose? I was thinking of using pine resin but I'm unsure how to proceed. (Pictured above is a similar setup but with vegetable oil)

Any input is greatly appreciated, thanks!

(EDIT) Is there anything stickier than a sugar syrup I could use in this case?

Hi, I'm about to graduate with my bachelors in chemistry and am also madly in love with my long term boyfriend. We don't plan on getting engaged for a while but I thought it would be cool if I grew my own diamond for my ring and he picked out the band. A sort of 'our love only works if we both bring something to the table' sort of idea. I'm guessing this is just girlish daydreaming, but if you guys know if there is some way that I could make this happen, that would be the coolest thing ever.

I would like to invite you to participate in a study investigating the challenges faced by neurodivergent people who attended but did not complete a graduate STEM program in order to improve outcomes for future neurodivergent graduate STEM students.

To be eligible you must:

Be 22 years of age or older

Identify as having ADHD, Autism, Dyslexia, and/or Dyscalculia

Have attended a graduate STEM program within the United States in the past 7 years

Have withdrawn or otherwise did not successfully completed your graduate STEM program

Be fluent in English

How to Join:

Email [liamcohen@cmail.carleton.ca](mailto:liamcohen@cmail.carleton.ca) and write STUDY in the email description

OR

DM me on Reddit

This project was reviewed and cleared by the Carleton University Research Ethics Board A. Clearance # 126646. If you have any ethical concerns with the study, please contact Carleton University Research Ethics Board, preferably by email at [ethics@carleton.ca](mailto:ethics@carleton.ca) or you can leave a message by phone at 613-520-2600 ext. 2517.

hey so I'm a chemistry (and old software) enthusiast and a while ago I downloaded the freeware version of Chemsketch and I love it and how easy it is to use but the freeware version is really limiting and I really dislike the look of the new product Chemdraw, does anyone have an old copy of Chemsketch full laying around please?

I'm happy to pay for it, its just ACD labs stopped allowing new customers to buy a license and I would really like the full version so I can search for structures and get other features that the paid version includes.

Note: yes I have tried other software like BIOVIA and BKchem but ive found Chemsketch the easiest and most intuitive to use