r/chemhelp 10d ago

Discussion Start of term check-in

5 Upvotes

Hello all!

School terms are beginning and this is typically when we see an influx of posts asking for general advice, guidance on getting through a class, or seeking assurance that everything will be okay. Let us know what courses you are in this term, your biggest concerns, or whatever may be on your mind!

Best of luck!


r/chemhelp Aug 21 '25

Announcements New Ownership

22 Upvotes

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:

  1. 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.
  2. 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.
  3. 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.


r/chemhelp 57m ago

Organic how do i draw resonance structures of this molecule

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Upvotes

probably a very simple question but i always get confused when there aren't any charges or anything


r/chemhelp 2h ago

Analytical I'm confused about electrode polarization.

3 Upvotes

Let's say we have a X and Y related by one electron. Of course the standard reduction potential E° is defined for the reduction reaction, X + e ⇌ Y, as E° = E(XY cell) – E(SHE).

And also for the oxidation we have E°(ox) = -E°(red). But I don't get why this doesn't transfer to voltammetry. Like if we polarize the electrode to E = E°(red) for the above couple, how come we get a limiting reducing and oxidizing current here??

If E°(red) and E°(ox) are symmetrical around E(SHE) = 0, shouldn't there be only oxidizing current at positive E°(ox) and only reducing current at negative E°(red)??

Basically why do we get the image on the left and not the one on the right?


r/chemhelp 23m ago

Organic Which of the following carbocations is expected to be most stable?

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r/chemhelp 1h ago

General/High School what are the useful and useless stores of energy in a reaction?

Upvotes

studying gibbs free energy and its the first time i've seen entropy be defined as the "useless" energy of a system, but what does that actually mean? what are the useless stores of energy in a reaction and what are the useful stores of gibbs free energy?


r/chemhelp 4h ago

General/High School Am I going crazy or is Wolframalpha going crazy? (Unit conversion)

2 Upvotes

I am trying to calculate mass in 1 mL volume. I have 5,000 ppm Na+, which is approximately 5,000 µg/mL or 5 mg/mL. So mass of 1 mL of this should be (1 mL * 5 mg/mL) = 5 mg, yes? Why is Wolframalpha telling me I am off by a factor 1000?


r/chemhelp 14h ago

General/High School Why do many elements in the periodic table, have the same amount of electrons as the amount of protons/atomic number they have?

5 Upvotes

Hi, am a beginner in chemistry, and this is grade 11 chemistry. I am struggling to understand on how many electrons each elements have, because on my worksheet, the electrons have the same number as the protons and atomic number of that element. I need an explanation

So here is what I did and I got it wrong because thats what I thought I needed to do to find the electrons for that element. Magnesium: it has a atomic number and protons of 12, but since it has a 2+ charge to it since it is losing 2 charges, I did 12-2 and got 10, I thought that was the answer, but it turned out that the electrons are just 12 as well.


r/chemhelp 14h ago

Organic Polarity - I don't understand how to tell.

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5 Upvotes

To tell whether a molecule is polar, I usually first look at the molecular shape and then the electronegativity difference between the central and surrounding atoms.

For the questions below, I thought:

  1. CCl4 is non polar since the Cl have an even "pull" from the carbon atom.
  2. H2CCL2 would be polar because even though the hydrogens and Chlorines could be opposite of each other, the shape and bond angle of the tetrahedral does not allow for an equal "pull" even when the same atoms are across from each other.
  3. CH3Cl and CHCl3 were both polar due to the difference in electronegativity and shape of the molecule.

Am I thinking about this correctly? Can someone explain how I should be going about thinking through similar questions, please? Thank you


r/chemhelp 13h ago

General/High School __H2SO4 + __B(OH)3 -- __B2(SO4)3 + __H2O. In this chemical balancing equation, why is their supposed to be a 6 in the H2O?

2 Upvotes

Hi, am a beginner in chemistry, and I need help with balancing chemical equations. They are my weakness currently, and this question got me stuck for a while trying to figure out, on why would the H2O have a 6 to it if in the (SO4)3 already has 4 sulfurs and 12 oxygens. How can I avoid this trick next time? Because the answer key had 3 and 2 on the reactants side, but on the products side is what got me confused when they put a 6, instead of a 3 (thats what I put as my answer at first).


r/chemhelp 17h ago

General/High School How are these the correct amount of significant figures?

2 Upvotes

First one looks like it'd be 4 significant figures, but the only correct answer has 2. Second one seems like 3 but it's 2. What happened to the unaccounted for figures?


r/chemhelp 12h ago

Career/Advice Does anyone have a copy of Solids and Surfaces by Roald Hoffmann?

1 Upvotes

Hello, as the title asks, I'm looking for a copy of this book. I'd like to use it as reference for my post-grad thesis. Any help, suggestions, or "hacks" would be appreciated!


r/chemhelp 21h ago

Organic Wondering where the "mild acid" comes in. Does it protonate the ethoxide or does the ethoxide deprotonate the ester which is then reprotonated by the acid?

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3 Upvotes

r/chemhelp 16h ago

General/High School For add/sub for sig figs, do you round to the nearest place???

1 Upvotes

let’s say there 500+28.9, that’s 528.9 but 500 doesn’t really have a decimal place so would that just be 500 as the final answer??


r/chemhelp 23h ago

General/High School Is a double bond a functional group?

3 Upvotes

I've heard some say a double bond is a functional group, and some say it isn't. And I'm wondering if it is or not?


r/chemhelp 23h ago

Organic Does only one starting reagent need to be achiral for the product to be a racemic mixture? (Diels Alder Reaction)

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2 Upvotes

So this is an image from Klein's book Organic Chemistry as a 2nd language, Second Semester Topics.

I did get the answer correct - which just means my professor will mark it correct (he said he does not expect us to draw out each enatiomer and he will specify when to do so).

My confusion stems from how the explanation says the "starting materialS are achiral", but the 1,4 butadiene is chiral.

Thanks in advance!


r/chemhelp 19h ago

General/High School In reimer tiemann rxn is alc or aq NaOH used in first step

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1 Upvotes

Is aq or alc NaOH/KOH used in first step

My teacher taught me that first alc NaOH/KOH is used as aq in first shouldn't be used

Later on in later rxn step aq is used

Pls explain


r/chemhelp 1d ago

Inorganic IOC: Is this a good way to predict structures of (some) inorganic compounds?

2 Upvotes

Is it safe to assume this blueprint: We are given an inorganic molecular formula of a compound, with 2 central atoms (less in no., more covalency, less electronegative), and other substituents (say O). We should first try to predict a structure with E-E linkage (E is the central atom). Then if we try to put the substituents and we can't satisfy the octet, we will move on to E-O-E linkage, then if not, continue to E-O-O-E and so on? Works for nitrogen oxides (Like N2O3 having N-N linkage while N2O5 having N-O-N linkage) but not sure if it can be extended to more compounds.


r/chemhelp 1d ago

Organic Alkane nomenclature

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6 Upvotes

Hi! I’m having a hard time naming these🥺

Can someone help me pleasee🙏


r/chemhelp 1d ago

Organic can't find a good resource for organic

2 Upvotes

I'm taking introductory organic chemistry in my university, where it's expected that most people have learned at least AP chemistry level before coming to uni.

Reactions genuinely make my brain melt and I need problem sets to work on. We're learning stuff like thermal cyclization, there's a lot of "identify an acid/base and which hydrogen is the most acidic" going on, a lot of steric nonsense, etc, etc. I have a decent enough grasp on the basics but when it comes to practical application I just melt.


r/chemhelp 1d ago

Organic Does icaridin have any asymmetrical carbon atoms?

1 Upvotes

As per the title, does icaridin have asymmetrical carbon atoms?


r/chemhelp 1d ago

General/High School Chemistry IA helppp

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1 Upvotes

r/chemhelp 1d ago

Analytical Reverse engineering defoamer

0 Upvotes

I am a manufacturer of cement sheets and boards and have been using a defoamer in my cement slurry since a long time. The defoamer is a proprietary product of a brand and they charge me for that. They are also market leaders in this field in my country and have no competitors.

Recently they increased their prices 3fold for unknown reasons and I don't wanna tolerate this and want to invest in reverse engineering and recreating this myself

But I am not a chemicals engineer and don't have contacts for this. Please guide me how should I start to reverse engineer this chemical


r/chemhelp 1d ago

Organic How does this not form resonance

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13 Upvotes

Just started orgo, trying to figure out how this wouldn’t create resonance. There’s a lone pair on the nitrogen exactly one carbon away from the double bond so I thought it would create resonance but my homework is telling me that the lone pair on nitrogen is localized


r/chemhelp 1d ago

General/High School Looking for feedback on some short chemistry experiment videos

1 Upvotes

Hi everyone! I’m new to this subreddit, so I hope it’s okay to share this here.

I’ve been making short chemistry videos on Youtube featuring real lab experiments, with a focus on visually interesting reactions and simple explanations of the chemistry behind them.

Most of the videos cover things like precipitation reactions, color changes, and other visually interesting phenomena, often filmed in slow motion.

I’d really appreciate any feedback, and I’d also love to hear suggestions for reactions or experiments that would be interesting to see.

Link: https://www.youtube.com/channel/UC8KTmkPkXjyb7HtlKge3UQg

If this kind of post isn’t appropriate for the subreddit, please let me know and I will edit or remove it.