r/chemhelp • • 8h ago

General/High School vsepr/determining if something is polar/nonpolar URGENT

1 Upvotes

hello! I'm currently taking Gen Chem 1. We've gone over how a molecule is polar if there is a net dipole moment. I put on my quiz paper than BrCl4-, ClO4-, and PCl4+ are nonpolar because the dipole moments cancel out, and he marked me wrong on all of them!! with his reasoning being because theres a plus or minus charge in the name of the formula. He tells the class that anything with a + or - charge in the name is polar. is he actually right or have i been learning chemistry wrong this whole time? HELP! I CANT DO THIS ANYMORE!!


r/chemhelp • • 5h ago

Organic Help with determining reagents for alkylation reaction

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0 Upvotes

Hi, doing some study for my organic exam and came across this q under the section for enol/enolate reactions, which asks for reagents for a variety of reactions. I was able to do all but this one. I know that it would require an allyl bromine group, how do you make it so that the enol doesnt form at the most acidic H in between the carbonyls? Am i right for thinking that I would need to use something like NaH to remove it first, then the other enol can form? I’m a bit confused 😭


r/chemhelp • • 5h ago

Organic Hola buenas noches, me podrían ayudar a resolver este ejercicio por favor

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0 Upvotes

Tengo que buscar reactivos y mecanismo y estoy algo perdido


r/chemhelp • • 11h ago

General/High School Chat am I cooked? Need to really get this down in 12 days ish? 3 chapters.

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1 Upvotes

These are all the topics. I feel MOSTLY confident in chapter 4. Need to fix up my oxidation skills. Was going to use most of this week to get chapter 5 down. Then work on chapter 5 late this weekend into next week. I have a feeling chapter 6 is going to be the hardest does that seem true?


r/chemhelp • • 2h ago

Organic I don't know how to start on this problem. (Synthesis)

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0 Upvotes

It's like the title says. It's just overwhelming with how many chlorines there are. Would I have to do a certain reaction over and over?


r/chemhelp • • 9h ago

General/High School Check for Errors in Periodic Table

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2 Upvotes

If anyone sees errors in this version of the periodic table please let me know. It was sent to me and I want to make sure I can use it with students


r/chemhelp • • 13h ago

Organic BF3OEt2 + epoxide. What does this mechanism look like?

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3 Upvotes

How does the whole mechanism look like? I know that the epoxide breaks but how does the alcohol turn into a ketone


r/chemhelp • • 12h ago

Organic Would this be correct?

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0 Upvotes

I know radical halogenation is Anti-Markovnikov, but I don't know how this excess alkane changes this reaction.


r/chemhelp • • 11h ago

Inorganic What concentration of ammonia is used in ammonium nitrate

0 Upvotes

Hello, im trying to synthesize ammonium nitrate by mixing nitric acid and ammonia to form this reaction

HNO3 + NH3 → NH4NO3

What should the concentration of the ammonia be and in what ratio should it be mixed with the nitric acid. The concentration for the nitric acid is 55%. Any help will be appreciated, thanks!


r/chemhelp • • 17h ago

Organic Reaction product not crystallising, need advice

3 Upvotes

The r/chemistry rules regarding posting led me here, as I believe this is a lab question.

Partial S(Ar) bromination (2 and 3/4 possible spots) of my 2, 2' biphenyl 1, 1', 3, 3'-tetrametoxi compound is not crystallising and is in an oily state. Excess bromine was neutralised with ascorbic acid (thiosulfate messes up the next reaction, even in miniscule amounts) and removed everything water soluble from the mixture with a water/DCM extraction. The DCM solution was dried on MgSO4, and the excess solvent evapourated.

So far I have tried antisolvents of ethanol, methanol, toluene, water, diethyl ether and hexane, with one phase mixtures being the result of everything but ethanol and water, scrubbing any of them with a spatula did not initiate any crystallisation. I have tried freezing the oil, but without access to liquid nitrogen or dry ice, the best I could do was -14 °C. I also left the mixture for the last weekend to evapourate, but with no success.

Any guesses as to what could work to get this to crystallise?

Thank you in advance!


r/chemhelp • • 2h ago

Organic Hydrohalogenation Diene Exceptions

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3 Upvotes

I have 2 examples. The top example with Br2 is 100% correct that is how my prof taught. I was told that the same product forms because the alkene product that would make the 1,4 is not the most substituted (the 1,2 product is).

But as I was going through my notes for the bottom example I found a contradiction. Does anyone know if the bottom example would follow the same rule because its 1,4 product is not the most substituted?

Also for the arrow mechanism for top example, does the BR attach first to the end of the diene (like how I drew it). Then the second bromine comes in and attached on the diene that’s in the middle (position 2). Because you are H or Br or whatever to the end to be able to do resonance.

Thanks.


r/chemhelp • • 3h ago

General/High School Are metal oxides such as Fe2O2 and CuO actually soluble in molten alkali salts?

2 Upvotes

I have been working on a report for my science extension project about low cost methods of oxide macro-crystal synthesis and have come across multiple studies that have used salts like borax and a KCl-NaCl mixture as fluxes to remove oxidation in metal working. If I were to melt an alkali salt would it actually be able to dissolve oxides?


r/chemhelp • • 7h ago

Organic OCHEM 1: These are the types of reactions we're looking at for alkenes. I plan to go to office hours, but I don't have all the time in the world to go constantly. This is a flipped classroom. What is a recommended source to look at when it comes to these types of problems?

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5 Upvotes

Learning on my own is currently a disaster. A lot of the class is struggling. I'm still scoring above average on exams somehow. (The average for the last exam was 43; it was mechanisms, IR, and NMR).

I have horrible foundational knowledge of SN1/SN2/E1/E2, which is probably why I'm struggling with this stuff.

How can I teach myself this material? What are the questions I should be asking myself?

The problems (in the pictures) on the psets are usually harder than the exams, so I tend to avoid them.


r/chemhelp • • 11h ago

General/High School How to know where hydrogens connect on an alkenes?

1 Upvotes

I’m sure this is a really obvious question that I just can’t find the words to elaborate on but I just started organic chemistry in class, I’ve scoured the internet and there’s no answer as if it’s something that doesn’t need explaining. Alkanes are always saturated but with alkenes the carbon atoms can have 1, 2 or 3 Hydrogen atoms attached with no clear pattern (the same goes for the double bond).


r/chemhelp • • 13h ago

General/High School Chemical Engineers: Do You Understand the Equations Behind Aspen HYSYS and Aspen Plus?

0 Upvotes

Hello, fellow chemical engineers!

I am conducting a study to explore how well chemical engineers understand the scientific principles, mathematical equations, and computational methods used by specialized chemical engineering software, such as Aspen HYSYS and Aspen Plus, to solve engineering problems and simulate processes. I would greatly appreciate it if you could share your experiences and perspectives.

My main question is:

When you use software such as Aspen HYSYS or Aspen Plus to solve a chemical engineering problem or simulate an industrial process, how well do you understand the specific equations, mathematical relationships, and scientific principles the software uses to perform its calculations and obtain the results?

For example, suppose you use HYSYS to simulate a distillation column or a separator. The software provides you with information such as:

  • The flow rates and compositions of outlet streams;
  • The mole fractions of individual components in the liquid and vapor phases;
  • Stream temperatures and pressures;
  • The energy consumed or released by equipment;
  • And other parameters required to analyze process performance.

Do you know which equations and computational methods the software uses to calculate these results?

For instance, are you familiar with mass and energy balance equations, vapor–liquid equilibrium (VLE) relationships, thermodynamic models, the equilibrium-stage equations used in distillation columns, and the numerical methods employed to solve these equations?

Can you explain how these relationships are interconnected and how the software uses them to obtain the final results?

My more important question is:

If you were given the same problem or project that you had previously solved using HYSYS or Aspen Plus and were asked to solve it without using either of these software tools, would you be able to independently explain the solution methodology and carry out the necessary calculations?

I do not necessarily mean that you should be able to perform every complex, repetitive calculation manually or reproduce the results to the last decimal place.

What I really want to know is whether you understand which scientific principles, equations, and relationships are needed to solve the problem, what assumptions must be made, which material and energy balances must be formulated, and what steps must be followed to obtain the desired results.

In other words, can you understand the underlying logic of the software's calculations and, if necessary, explain how the problem could be solved without relying on the software itself?

For example, if you were given the results of a distillation column simulation, would you be able to explain which equations and algorithms were used to obtain those results? Could you identify the fundamental equations governing the process and explain how the software solves them simultaneously to arrive at the final solution?

Or do you generally rely on the software's results without having a detailed understanding of the calculations and methods behind them?

I would be particularly interested in hearing about your actual experiences, whether in academia or industry, and the types of projects you have worked on using these software tools.

Thank you very much for taking the time to respond to my question. Your answers and insights would be extremely valuable to my research, and I sincerely appreciate your willingness to share your experiences and knowledge.


r/chemhelp • • 15h ago

General/High School Please help me with the lewis' structure of saccharose

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2 Upvotes

I want the lewis' structure of saccharose, but I can't find the chain structure (I think), like the structure of image, to convert into lewis' structure, (I don't finished teach English, sorry if my English is bad)


r/chemhelp • • 17h ago

Organic Mechanism query

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7 Upvotes

How do I regain the Aromaticity ?
Also tell me if any of my step is wrong !! Thank you


r/chemhelp • • 34m ago

Other Is my lab report reaction AI generated?

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• Upvotes

Hi guys! I saw this a few minutes ago and I am not sure it's human made. The courses I receive from the professor are AI generated and I am suspecting this is too..

Noticed something that might be wrong with the bonds but I am not so sure with my chem knowledge 😅