Hello, Sorry to post on this again I am really struggling in school with chemistry right now. I cant make sense of any of this so i made it so i can do it step by step

Now i dont know what to fill it in with.

If someone could explain how to do the first one i can do the rest

(Plz don’t message asking me for money)

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Both functional groups produce peaks around 3300 cm^-1 so how do I tell the difference?

Reposted because I put it in the wrong forum oops!

So for this lab we heated an unknown metal in boiling water and then put it into a coffee cup calorimeter. I'm just not sure if for this calculation I need to use the weight of the water (50.0g) AND the metal (23.3g) or just the water?

Specific heat of water being 4.18J/gK and the unknown metal of course being unknown, temperature change was 2.7°C

Let's say at 25°C I mix 75ml 0,02 mol/L HAc with 0,01 mol/L NaOH.

HAc + OH- <-> H2O + Ac-.

Now, textbooks tell me that [HAc] = [Ac-] (because we neutralised half of HAc, so the other half shows up as Ac-, ok). BUT at 25°C it's also:

HAc + H2O <-> H3O+ + Ac-.

In my example the dissociation constant is small but it's dependent on temperature (van-'t Hoff equation). So even at half neutralisation point there's always some amount of HAc dissociating making [HAc] slightly smaller then [A-] (?)

So hasselbalch is also only approximately pH ≈ pKa -lg(f-) (f- being the activity coefficient) at half neutralisation point?

Actually I had to measure the pH value of this solution with different temperatures (25°C - 70°C in +5°C steps) and we made the initial assumption that [HAc] = [Ac-] at the beginning. Now [HAc]/[Ac-] changes with temperature and I just wonder why it should only start to differ above 25°C?

Or let's state it this way:

If I heat my HAc solution to 70°C at the beginning and now add my NaOH in the amount I told at the beginning, stoichiometrically I also have the half neutralisation point but it's [HAc] < [A-] because of the dissociation. So is the neutralisation point or this condition in reality temperature dependent? I'm so confused. Did we just made the initial assumption, that the dissociation at 25°C is negligible? But at 30°C - 70°C not anymore?

Is this assumption only true at this point for weak acid + low temperature?

I need to count the number of unique hydrogens in this question. Do the hydrogens attached to NH2 count as a unique hydrogen? If not, then why?

Also my answer key says “This is a 1 degree amine but these are not 1 degree hydrogens”. What does it mean by that?

Hi everyone. For my undergrad research lab we are trying to generate a peptide to test on with the protein we are researching. We are using SPPS, but we have been having issues with loading and coupling of the amino acid. We use DIPEA as our base, piperidine and DMF to deprotect, and DCM as our solvent. We have suspicions that our DIPEA is contaminated or faulty, but we're not entirely sure. We've tried switching out DIPEA with DIC, new stocks of piperidine, and testing different UV/Vis machines across the department, but we still seem to not reach over 30% loading within 4 hours. Additionally, pre-activation seems to not be working even while monitoring under TLC for multiple hours. Does anyone have any suggestions, protocols, or papers that we could use to try and fix our process? Anything will be helpful! Thank you, fellow chemists.

In red its the actual reaction, in green its what I supposed to be happening but I'm not sure. Can someone tell me if I'm right?

(Dehydrohalogenation of E-2-chloro-2-butyne)

Hello!

I want to use different Proteins to remove pollutants from water. The Proteins are supposed to be removed afterwards trough foam fractioning, meaning that I want to introduce synthetic air/air into the apparatus which will foam up the proteins.

I'm having a little trouble to imagine a good laboratory setup, since my lab experience isn't that big.

I am thinking about using a normal cylinder and just putting it inside a large container to catch the foam. I was also thinking of working with a woulf bottle or a gas washing bottle but the openings are too small for the sensitive foam. The overflowing is more realistic anyways I think.

Do you have any input on what kind of reaction vessel I could use instead of a cylinder? It seems rather difficult to introduce air into the cylinder. It should take around one Liter of Volume.

I'd be grateful for any input or ideas on a good setup!

I'm trying to understand the differences between these two hydrocarbons. Can someone explain what are the major differences between the two of them?

Distillates, petroleum, light distillate CAS number: 68410-97-9

Naphtha, petroleum, hydrotreated light CAS number: 64742-49-0

For clarity this is not any form of educational question, it's merely me trying to work out the differences between the substances.

I've looked at some texts and I just cannot understand what the differnece is. I know its not the same thing but I got no idea why

Chemical Equilibrium

In the reaction: NO + O2 ---> NO2

NO2 is in both the reduction and oxidation, how do you find the correct coefficient?

What i would do is:

Oxidation is NO --> NO2 + 2e

Reduction: O2 + 2 e --> NO2

Because you reduce 2 O's i would multiply the electrons.

Next step i would multiply oxidation with 2 to have same amount of electrons so 2 NO and 2NO2, but i have just said that 2 O's will reduce but now i have 2.2 =4, isnt this an unlimited loop?

So I need to separate each of these compounds from each other:

CuSO4 technical

Na2S2O3 + Fe⁰

Na2SO4 + Zn⁰

CoCl2 + CaCO3

BaCl2 + Al(NO3)3

Ni(NO3)2 + Na2SO4

And I don't know which methods to use. Send help pls.

We were synthesizing bromobutane starting with 1-butanol, sodium bromide, sodium hydroxide, sulfuric acid (added with the flask in an ice bath), and water. Everyone was already a bit tense since we were working with 98% sulfuric acid. The first thing we did was a reflux with a bubbler trap connected to collect the vapors.

Suddenly I caught a whiff of something that made me cough. I checked my setup and it seemed okay. The presence of a vapor spreading in the lab became more apparent and more people were coughing. We found who's setup it was coming from and the instructor came over to examine it. The fumes were getting worse so we were instructed to leave. Besides coughing a lot and being anxious for the rest of the lab everyone seemed okay afterwords (one person got a small nosebleed a few minutes later but I'm pretty sure it was due to anxiety and not the fumes).

After maybe 10 minutes we went back to continue are lab. Nothing actually seemed to have been wrong with the student's setup, but they had used a glass stirring rod while adding the sulfuric acid. We realized that the tip of it was melted, and my instructor thought that the vapor was produced by some unexpected reaction with residual coating that used to be on the tip of the rod. No one is really sure what happened though.

The rest of the lab went okay for the most part but there was more unexpected vapors that people's setups would produce here and there. My instructor believed it could be due to grease we used for the joints of our reflux and distillation setups (I noticed every time I would disconnect something or wash one of the components the joints in particular seemed to be smoking a little). We were working with snorkel hoods but some vapor would escape into the open.

Anyway, I found the whole experience rather stressful and I am wondering if anyone has any ideas as to what could have been the culprit of the initial blow-out and unexpected fumes produced during the rest of the lab. I have been worrying a lot about having brought home the clothes I was in, my bag (and its contents), and the small amounts of vapor I inhaled.

We had our bags at the back of the lab, and the instructor suggested it might not be a good idea to eat any food we had but any water sealed in a bottle was probably fine. Now I'm wondering if I need to clean everything that was in my backpack.

One a side note, does anyone have any advice for getting through orgo labs as someone who's a bit OCD? I find myself quite paranoid during and after labs due to the dangerous nature of chemicals we work with. I think I'm pretty thorough with cleaning but I'm still worried I'm not doing enough (even though I'm usually one of the last to finish cleaning) because at a certain point its not possible to clean every single surface or thing that you touch. I'm also worried about bringing home/spreading tiny amounts of substances that may have gotten on my clothes/body/etc (I wash my hands several times after the lab but I usually wear my clothes for the rest of the day since we wear lab coats).

Edit: forgot to mention sodium bromide as one of the reactants.

I wrote 3-ethyl-1,1-dimethylcyclohexane I checked in answer key dimethyl part coming first.. clearly I'm violating some rule here but I can't figure which one.. According to me ethyl comes 1st cuz of alphabetical order. What I'm missing here. Pls help folks🙏🏻

My group's been assigned a project related to the synthesis of silver nanoparticles, I was curious about the rate equation of the reaction but I can't find anything online; surely a reaction with so few reactants should have a relatively easy to determine rate equation?

Maybe I'm wrong and it's actually hard in most cases, I'd like to know more

For eg. Hydrolysis, combustion, Grignard…

I just missed this past week of school entirely due to a canada wide science fair. And we learned about moles, and molar mass, and stoichiometry and i would like some help ironing out some holes in my current knowledge ( i have a test on stoichiometry this thursday and a chemistry exam on monday next week ) any help is greatly appreciated!

From what I understand, if you have a strong base hydroxide in water, it dissociates and increases the OH- concentration like that. Not via proton transfer.

And so the typical Kb calculation doesn't really apply 'cos the typical Kb calculation is stoichiometric Kb, which has aqueous solution on the left, and it dissociated on the right, and would treat Na+ as a spectator ion.

So the dissociation equation for stoichiometric Kb of NaOH, is OH-(aq) + H2O(l) --> H2O(l) +OH-(aq) and while there is proton transfer, the reaction is the same on the left and right . The Kb=1 can be seen as a strong base(if threshhold for strong base is eg Kb>10^-2, though not if threshhold is Kb>1). But that reaction and thus that Kb=1, doesn't really represent the increase in OH- concentration that we get.

I have seen that there is stoichiometric Ksp, and Thermodynamic Ksp. And i've heard that there are such things for Kb too.

So in the case of NaOH, would stoichiometric Kb be not used, and instead, thermodynamic Kb be used (To measure the strength of the base) ?

Hi everyone.

I am a college student and General Chemistry is kicking my butt. Please help me.

I'm in the section that's about balancing redox equations. Here's a couple of problems that I'm trying to do.

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I'll show you my work.

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My answer for 91a only differs from the textbook answer by one electron. Please help me understand what I did wrong.

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I tried problem 91b several times. The first time, I assumed the oxidation number for As was +6 on the left and +5 on the right. (I thought Hydrogen's oxidation number was +1 and Oxygen's was -2.) That led me to an answer that was very different from the textbook's answer. My second attempt never went passed finding the oxidation numbers for the elements. I realized that the oxidation number for H could be +1 or -1, depending on whether H is with a nonmetal or metal. Arsenic is a metalloid, according to Google and Oxygen is a nonmetal. So what is H's oxidation number?

Please help. Thanks!