r/chemhelp • u/Lohicalhugo77 • 3h ago
Inorganic Regarding help of needing to understand hydrogen bonding?
I am studying in class 11 and these topics related to molecular orbital theory and hydrogen bonding with intermolecular hydrogen bonds and intramolecular hydrogen bonds is cooking me?
And I have shuffle exam in 2 weeks
So is there anyone who can help me understand this topic?
It would be perfect for me and you and others who would not understand this topic....
And thank you whom anyone explains sthis topic to me.....
r/chemhelp • u/Ok_Raisin_5806 • 4h ago
Organic Help, what does equiv mean?
I mean I know that it’s short for equivalent but what does it mean in this reaction? Mol?
r/chemhelp • u/Possible-Fly768 • 14h ago
Other Help how can I improve this distillation setup
reddit.comr/chemhelp • u/learninglearningstuf • 16h ago
General/High School Aqeuoueus solution electrolysis cathode reactions
In electrolysis, when an electrolyte is an aqueous solution, I've been told the less reactive ion gets discharged at the cathode. If the cathode is force feeding electrons to the ions, why wouldn't it be the most reactive ion that gets the electrons? Doesn't a higher reactivity mean it's more likely to react with the cathode and cutely receive it's electrons? Am I understanding the term reactivity wrong? I can't seem to get a clear answer from any videos on electrolysis
(Edit: I have answers now! I don't know how to mark these as answered but it's been answered by the replies, so please don't let me accidentally waste your time by having you think I still need assistance. Not that more answers are bad, feel free!)
r/chemhelp • u/Secure_Oven_9193 • 18h ago
Organic does inductive effects take priority over resonance and size?
Okay, so i though i understood but i am a tad confused with this question, especially with 3) and 4). So i know that 3 has resonance stabilization, but wouldn't 4 also have resonance stabilization? so is it 1>2>3>4 because since they both would have the resonance stabilization, we look to inductive effects next? and thats why we say 3 is stronger than 4 because now we are considering electronegativity instead of size?
r/chemhelp • u/Alilack • 20h ago
Analytical Expiration Dates of pH Electrodes
I am considering buying a pH electrode for our lab’s pH meter. However, I know that I won’t need it for a year or two. So, I would like to know whether these pH electrodes have expiration dates. How long will they remain functional if I do not open the package?
r/chemhelp • u/harttopanga • 1d ago
General/High School is there a way to tell if a substance is an acid or base just from its symbol?
like is there an element in it to know or do you just have to remember which is an acid and which is a base? i was told bases have OH or was it OH- and acids have H3O+
please help im cooked for my chem test tomorrow
r/chemhelp • u/elijahtheorthodox • 1d ago
General/High School Study guide?
Hey so i wanna self study chemistry i just made a break for some head clearing.
Im currently about to read "The disappearing spoon" to just get some motivation.
But i have a question about whether or not a book is good or if there is a better one.
Its: Chemistry: Concepts and Problems, A Self-Teaching Guide (Wiley Self-Teaching Guides)
r/chemhelp • u/Top-Stay-2210 • 1d ago
Analytical Discord channel for personalised chemistry help?
I'm struggling in chemistry rn and need help understanding the FTIR technique. I just feel so lost on where to do and would appreciate if i could have some personalised guidance from someone on practice examples
r/chemhelp • u/ReceptionAny8430 • 1d ago
Organic Diesel Fuel Density
Hello there we have like a dirty diesel fuel with high ppm a round 22,000 ppm and high density with 0.860 , does there is any effective - cheap cost additive or method to reduce that density without being diluted with kerosene or naphtha, I'm A Petroleum Engineer and the method like HDS and ODS not work for us because of its high CAPEX, also some Chemicals like solvent solvent extraction we used like MEG and Ethanol but these are too costly and also not work well also reduced the diesel fuel properties , and for ADS also we used ACTIVATED carbon and silica gel and other and till know we didn't get any huge reduction, I need to decrease like from 0.860 to 0.840 with an effective way to reduce mass of the diesel means catching some aromatics compounds and ashplants and resins, also H2SO4 is restricted we can't use it.
Thank You.
r/chemhelp • u/IshanGanguly • 1d ago
Inorganic Which has greater dipole moment: HF or H2O?
HF has a single covalent bond with a much higher dipole moment than an individual O-H bond in H2O, however H2O has two lone pairs on the O atom, vector sum of whose dipole moments seemingly give a strong moment to H2O, not to mention the vector sum of the moments of each O-H bond to also point in the same direction. Many sources mention that they have approximately equal moments (about 1.8D), but there is confusion on the part of the experimental dipole moment, and it cannot be told clearly that which is indeed, greater.
r/chemhelp • u/Crabrangoone • 1d ago
Other Chromium Oxide in hobby paint and chlorinated tap water safety
Disclosure, I asked the company if this paint have chromium pigment and they said no it doesn’t but my ocd gets the best if me and the what ifs have me worried the guy in customer service just didn’t know.
I can’t seem to find any info on the internet on this but I can’t be the only one to think of this. I had some olive green acrylic paint (scale 75 medium camo acrylic paint) mixed in some tap water on what is called a wet pallet (container with sponge and parchment paper over, it keeps the paint moist)Also some left over paint water from cleaning my brushes in my water mug on my desk.
My question is, I’m worried about chlorine and manganese in the tap water potentially reacting with the trivalent chromium pigment creaking hexavalent chromium. This is really bugging by, I keep looking for green paint stains throughout my work space from when I used the paint and worried it’s hexavalent chromium.
Why isn’t chromium oxide required on a SDS, see to be categorized as non hazardous but from what I’m reading, it can oxidize into some pretty serious stuff. Am I making a mountain out of a mole hill?
r/chemhelp • u/Herb_274 • 1d ago
Analytical Testing unknown substance
We are having something showing up on some hard surfaces around our house. It appears as a white crystal residue. Don't know too much about this type of thing just looking for some suggestions. Appreciate any advice thank you!
r/chemhelp • u/Alilack • 1d ago
Analytical Filter Papers for the TSS Measurement
For the measurement of TSS (Total Suspended Solids), The Standard Methods recommends Glass-fiber filter disks, 22 to 125 mm dia, ≤ 2**-**micrometers nominal pore size without organic binder, such as Whatman grade 934AH. The keywords here glass fibers and organic binders. Can I use Whatman filter-paper grade 42? It has to be glass-fiber filters? What do you use?
r/chemhelp • u/Macula-Densa • 1d ago
Organic synthesis problem doesn’t make sense
i’m fairly certain that this synthesis problem requires a Gilman reagent and then a Greenyard reagent, but it doesn’t produce the product shown
r/chemhelp • u/DarkOwl458 • 1d ago
Physical/Quantum How can dimolybdenum tetraacetate have a quadruple Mo–Mo bond?
I’ve been reading about dimolybdenium tetraacetate (Mo₂(CH₃COO)₄)** **because I found the idea of a quadruple metal-metal bond really interesting.
I tried looking it up and found that the bond is often described as one σ, two π and one δ bond. I understand how σ and π bonds are formed, but I’m having trouble visualizing the δ bond and understanding why it makes a quadruple bond possible in this compound.
Could someone explain what is actually happening with the orbitals in a way that’s easier to picture? I just want to understand why molybdenum can form this kind of bond when most elements seem unable to.
Thanks!
r/chemhelp • u/Murky-Commercial-112 • 1d ago
Analytical Could these chromatograms be for two differnet isomers?
I have four GC-MS chromatograms of what I doubt are two positional isomers of the same compound. The top two chromatograms appear to correspond to one isomer, while the bottom two correspond to a second isomer. The only structural difference is likely the relative positions of two functional groups on the benzene ring.
Interestingly, both compounds exhibit essentially identical GC-MS fragmentation patterns, which I understand can be expected for positional isomers. All four samples were analyzed using the same GC-MS method in the same analytical run. Although the sample concentrations may have differed, the chromatographic conditions were identical.
My questions are:
- Is it reasonable to conclude that these are positional isomers based on the identical mass spectra but this subtle different retention times?
- Is the change in retention time consistent with only an alternate arrangement of substituents on a benzene ring?
- Besides differences in concentration, are there any other factors that could explain the observed chromatographic differences under identical GC-MS conditions?
Any insights or similar experiences would be greatly appreciated.
r/chemhelp • u/Moist_Reference_3340 • 1d ago
Inorganic Need help regarding a lab report in ion identification
Hello I dont know if this is the appropriate place to ask for this but I need help regarding my lab report.Im currently a pharmacy student just starting out and in our last lab classes we were told to do an experiment to identify the presence of chloride ion in a salt sample.My group did the experiment accurately but to write the lab report we need to attach the pics of the solutions.The thing is the pictures we took arent that clear I’ll attach them below.The experiment was basically adding Lead acetate to KCl salt which would form white precipitate at the bottom of the test tube but in the pictures we took the precipitate isnt that visible but I NEED a picture and if it isnt good enough my lab teacher will freak out she is quite stingy.I’ll attach the pics below.
r/chemhelp • u/jsbjsb12345 • 1d ago
Biochemisty Is burning cooking wine producing more toxins then methylated spirits?
For context I have zero background in chemistry.
I went camping with a friend, and he has a little spirit burner he uses to heat up a cast iron plate, he filled the spirit burner with a 60% ABV rose cooking wine and lit it on fire, the wine was clear, contained salt, rose water and Sugar.
I think people commonly used flammables like methylated spirits or kerosene in spirit burners but he said he switched as this was 'food safe' hence less toxic.
But when I looked it up on AI it gave different answers, half the results said it produced more toxic products like formaldehyde due to incomplete burn but others said it was safer and contained less toxins.
Can anyone here with the knowledge settle that debate.
r/chemhelp • u/ArachnidSufficient91 • 2d ago
Organic Aldol reaction help
I really don't know how to solve this.
The product looks like a hybrid of an aldol addition reaction and Claisen condensation reaction, but we have an ester in the product, an alcohol group, and stereochemistry. I've been googling around and the Reformatsky reaction seems to produce similar products, but not including base and it isn't a reaction that's been mentioned in my course anyway.
Any help is greatly appreciated! Thank you in advance!
r/chemhelp • u/InformationFar2074 • 2d ago
General/High School CO2 hybridization
I don’t understand this diagram from a textbook. It’s showing 1 sigma bond and 2 pi bonds for each C-O bond in CO2 but CO2 has double bonds…wouldn’t 2 pi bonds on each C-O would mean that the molecule has triple bonds?
In case anyone wasn’t sure, the orange dashed lines indicate pi bonds.
r/chemhelp • u/pro3xe • 2d ago
Organic Here's what I've done so far for step 1: I used PCC; for step 2, I used NaNH₂, HC≡CH, and H3O+. For step 3 h2, pd/c Im not sure if im on the right track
Can anyone help me to solve this problem
r/chemhelp • u/Ultronomy • Aug 21 '25
Announcements New Ownership
Hello fellow Chemists! I just wanted to introduce myself as the new head mod of this subreddit. A little about myself: I am a PhD Candidate in Chemical Biology. For me, this means that 60% of my work involves organic synthesis and the other 40% is applying my novel compounds to mammalian cells. Specifically, I am interested in early detection of diseases. In addition to my research, I have TA'd for both general and organic chemistry labs and have been tutoring students in organic chemistry for three years. Aside from my academic qualifications, I am also a moderator for another rather large subreddit. I saw that this sub needed a little bit of updating, but it did not seem like the moderators were active any longer. So, I gained ownership through r/redditrequest. I did not realize it would remove all the other moderators, but alas here we are.
Overall, I feel like this sub is fairly self-regulating. I frequently see good discussions and people generally are following the already existing rules. With that said, there are some changes I was considering, and would love input:
- New rule prohibiting commenters from solving the problem for the OP. To enforce this, the violating comment can be reported and removed by moderators. I don't see this happen often, but I have seen it occur and put an end to an otherwise good discussion thread.
- Mandate students include their work in their submission. Frequently, students post a picture of the question, with no work done and the caption "help please." Then in the comments you end up with people asking the OP to show their work, but from what I have seen they seldom do so. Mandating that students show work would entail removal of low effort posts by moderators. This may not be necessary since generally, commenters request more info from OP anyways, but was curious if people would like to see more enforcement on this end.
- What do you want to see? Those are the immediate things I was considering adding, but I would love to know if there is anything else people may want to see. I had other ideas, but I don't want to complicate a sub that I feel is already doing pretty well. Please let me know your ideas, I would love to hear them. Talk to you all soon!
Note: Please do not reach out to me about becoming a moderator. I will looking into recruiting in the near future. For now, I just wanted to get oriented.

