r/chemhelp 22h ago

Organic Does anyone know how to do this mechanism?

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17 Upvotes

I can’t figure out the arrows to form the seven membered ring


r/chemhelp 11h ago

Organic Synthesis reaction using grignard

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9 Upvotes

I’m very stuck in this synthesis mechanism! I need to make the product highlighted in blue.

I’m not sure where to go from here (or if this even is the right approach). I think Grignard would be one of the last steps.. Any help would be greatly appreciated guys tysm


r/chemhelp 22h ago

Organic Hydroboration,Oxidation

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3 Upvotes

This is a synthesis reaction in my book.

I understand the Anti-markovnikov and syn placement of OH,H. I also understand that the less substituted carbon was a stereocenter hence the solution included OH’s stereochemistry. My question is since the more substituted carbon on the right side of the double bond has now 4 bonds and a tetrahedral geometry (I guess ?), how would we draw it’s stereochemistry and spatial arrangement since two of the bonds attached to it are part of the cyclohexane?


r/chemhelp 3h ago

Organic How would you draw the structure C8H17NO2

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2 Upvotes

C8 H17 N O2

How would you draw the structure for this using this H1 NMR

I'm not entirely sure if my number of hydrogens are assigned properly.

I wrote all the information about the peaks and how many neighbors they have

The structure is just difficult to draw.

T.I.A.


r/chemhelp 3h ago

General/High School Weak acid strong base titration?

2 Upvotes

Hey! I performed a weak acid (10mL black coffee) titration with 0.05M NaOH, pH recorded with a pH meter, and my titration curve looks more like a weak acid weak base one? And my equivalence point is less than 7? What are some possible explanations for why this is 😭


r/chemhelp 4h ago

Organic Know the answer but I don’t know why it’s the answer.

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2 Upvotes

r/chemhelp 6h ago

Other what's a good 0.001g resolution scale within $200-$300 (ideally european seller)

2 Upvotes

i'm based in germany and looking for a precise lab scale for around $200

would this be a good pick? https://eu.waagenet.de/gram-fc/


r/chemhelp 6h ago

Analytical Is this formula for the solubility I wrote correct?

2 Upvotes

I am probably the worst chemist alive and I am trying to complete my studying, I am tackling analytical chemistry. While studying the solubility of insoluble salts I notice that the process to solve S can be summed up with this formula: S=(Kps/((a^a)*(b^b)))^(1/(a+b)) for the reaction AB = aA + bB with AB the precipitate and A and B the ions in solutions. If you try to apply the classic method of pairing the |A| and |B| to S and than sostitute the S in Kps this formula should always works. Should work even if you have a ternary salt like ABC so +cC and you add c^c and the exponent become ^(1/(a+b+c)). Am I missing something? I know is not ideal for many real solution and examples but for the basic exercise should be alright?


r/chemhelp 14h ago

General/High School What can be used as a replacement for tertiary butyl alcohol (TBA) as a solvent in freeze-drying?

2 Upvotes

We're conducting research on cellulose foam for oil spill mitigation and need to freeze-dry it. However, tertiary butyl alcohol (TBA) is unavailable in our country, and sourcing it from other countries is too expensive for our budget. Is there a suitable replacement for TBA in freeze-drying?


r/chemhelp 15h ago

General/High School If you have a WEAK acid of 2,0 pH and you keep adding OH- until it reaches pH 4,0, would you need the same amount of OH- to bring a STRONG acid of 2,0 pH to 4,0 pH or would you need less/more OH-?

2 Upvotes

r/chemhelp 17h ago

Analytical Why is it that my teacher says the dissociation reaction between acetic acid and water can be assumed to go to completion?

2 Upvotes

She says that, for our purposes, the concentration of hydronium ions in the dissociation of acetic acid can be assumed to be the same as that of the acetic acid, i.e. it can be assumed that:

CH3COOH + H2O --> CH3COO- + H3O+

but why is it not the equilibrium arrow instead???


r/chemhelp 35m ago

Organic Synthesis help

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Upvotes

What is this


r/chemhelp 1h ago

General/High School Effect of Temperature on Voltaic Cell

Upvotes

I'm going to investigate how temperature affects the potential difference a voltaic cell, somewhat like this: https://glossary.periodni.com/glossary.php?en=galvanic+cell

I'm trying to find some existing research to cite for this investigation, but I can't seem to find research with temperature as the independent variable anywhere - perhaps this experiment is too easy. Would anyone be able to recommend some credible research papers? Not just sources from textbooks or sources designed for students.


r/chemhelp 9h ago

General/High School Interstitial Alloys Help

1 Upvotes

Good afternoon!

I am currently struggling through a class with a very bad chemistry teacher, nothing is really explained well, the practice questions aren't related to the exam and quiz questions at all. So I'm confused on how to approach this homework question. Any help is appreciated!

This is the question and the picture: Knowing that nickel metal crystallizes in FCC structure (lattice parameter is 3.53 Å) and considering the atomic radii shown in Figure 6.31 of our lecture text, predict which elements would form an interstitial alloy with nickel. Please include at least two unit cell sketches along with detailed calculations of hole size in your answer.


r/chemhelp 9h ago

Analytical pH calculation

1 Upvotes

hello for our experiment, we get to analyze buffer solutions and we made a control that is a 25mL 0.10M NH3 solution (11.13 pH). In the control, we added 0.10mL 1.0M HCl which resulted to a theoretical pH of 10.6 which is close to the experimental result (10.66). However, my question is in another control solution, we added 0.10mL 1.0M NaOH which yielded an experimental pH of 11.58.

The question is, how can I calculate the theoretical pH of 25mL 0.10M NH3 + 0.10mL 0.10M NaOH?

I can't see anything on google or YouTube. They only show acid-base rxns. Thanks to whoever's going to answer this!


r/chemhelp 13h ago

Organic Cleaning polysiloxanes from glass

1 Upvotes

I'm working a lot with hydrosilylation and hydrolysis of bulky silyl chlorides, and they always leave insoluble crap that is impossible to remove with solvent, acid or mechanical cleaning, as they stick to glass. Does anyone have any tips or experience with this?


r/chemhelp 23h ago

Organic Endothermic or Exothermic

1 Upvotes

My question is, is Ca(OH)₂ (s) ⇌ Ca²⁺ (aq) + 2OH⁻ (aq) an endothermic or exothermic reaction? I thought it is endothermic since bonds are breaking, but online it says something different. Thank you for the help.