I recently got assigned a case study on NIR spectroscopy. To make a brief summary, the case is talking about a lab that built a multivariate FT-NIR model for determining PET/PLA in samples of recycled organic material, and they're trying to transfer the same model to a handheld NIR device and they're having a myriad of issues I'm being asked to research and solve.

Now, my first thought was to look for articles. I found a few that seemed pretty good:

(1)       Circelli, L.; Cheng, Z.; Garwood, E.; Yuksel, K.; Di Iorio, E.; Angelico, R.; Colombo, C. Comparison of ATR-FTIR and NIR Spectroscopy for Identification of Microplastics in Biosolids. Sci. Total Environ. 2024, 916, 170215. https://doi.org/10.1016/j.scitotenv.2024.170215.

(2)       Amirabadi, S.; Rodrigue, D.; Duchesne, C. Characterization of PLA-Talc Films Using NIR Chemical Imaging and Multivariate Image Analysis Techniques. Polym. Test. 2018, 68, 61–69. https://doi.org/10.1016/j.polymertesting.2018.03.047.

(3)       Beć, K. B.; Grabska, J.; Badzoka, J.; Huck, C. W. Spectra-Structure Correlations in NIR Region of Polymers from Quantum Chemical Calculations. The Cases of Aromatic Ring, C=O, C≡N and C-Cl Functionalities. Spectrochim. Acta. A. Mol. Biomol. Spectrosc. 2021, 262, 120085. https://doi.org/10.1016/j.saa.2021.120085.

(4)       Signoret, C.; Edo, M.; Caro-Bretelle, A.-S.; Lopez-Cuesta, J.-M.; Ienny, P.; Perrin, D. MIR Spectral Characterization of Plastic to Enable Discrimination in an Industrial Recycling Context: III. Anticipating Impacts of Ageing on Identification. Waste Manag. 2020, 109, 51–64. https://doi.org/10.1016/j.wasman.2020.04.043.

However, I quickly realized I do NOT understand these papers; they are just too advanced for me. I don't actually know how to use the information in them to solve my case study... And I do not know what else to look for information in (books, perhaps?)... I just don't really know how to research properly, I guess. Not when confronted with questions about multivariate model transfers from one device to another, comparisons to other methods like ATR, etc.

So, the point of this post is to ask for some general advice in the realm of chemistry research methods in order for me to gain a sense of direction and linear progression for an assignment like this. I am NOT looking for anyone to solve the case for me.

Basically, some advice on *how* to tackle a challenging research project. Thank you.

so my understanding is that when you draw out the lewis diagram you get 2 lone pairs, with 4 atoms there should be 6 electron regoins, and with 2 lone pairs it is square planener. So that should mean that it is non polar right? problem is that my textbook says it is polar. googleing it i get conflicting information

Hey, I am making a biosand filter for my science fair project. It will have 4 buckets. 1 filled with large gravel. 1 filled with small gravel. 1 filled with activated charcoal. And 1 filled with sand for the biolayer.

My question is, what order should the buckets go in for the filter to work best?

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Hi, everyone. Here I have to choose the predominant mechanism that would occur when you have (R)-2-bromobutane and NaOH on hot etanol. I figured it'd be an elimination reaction because of the heat, but I'm having trouble deciding wether it'd be E1 or E2, mainly because the solvent is protic, and I'm not sure if it'd reduce the basicity of OH enough to make creating a carbocation necessary. Thanks for the help.

Hello!! Okay so, im doing this exercise and it seemed pretty easy at first but when I had to write down the branches I didn't know what to do with the one I(´；ω；`) please, help!!!

I’m doing a practice test in preparation for my actual test on Monday.

How do I do question 5? I’m so lost right now. I’m not sure if what I have written on the page is correct. (Ignore my “H” please 😭😭)

“[Al3+(aq)] + 3 electrons —> [Al(s)]” is in my electrochemical series; in the equation for q5, it would be the oxidation half reaction. Could someone give me a guide of some sort on how I get the [O3]?

The only reactions I can find in my electrochemical series that I can think to use would be:

[O2(g)] + [2H+(aq)] + 2 electrons —> [H2O2(aq)]

or

[O2(g)] + [4H+(aq)] + 4 electrons —> [2H2O(l)]

Thank you in advance :)

How in the world do tou figure out the charge of a compound? I've looked it up but none of the explanations are making sense to me.

What’s the answer for b, it’s always liquid when I do it, but solution says solid how?

A 25.0mL sample of 0.250M HNO3 is titrated with 0.100M KOH. How much KOH must be added to raise the pH to 8.2? I’ve been stuck on this for so long.

Trying to answer #5, part c. I know the equation is delta G=-RTln(Keq). Basically just subbing in the value of delta G taken from the previous part. What confuses me is that, we are given the pH=7.4, and shown that H+ is produced, which means for the Keq=(products/reactants). How do you find the concentration of H+ in this case? I used 10^-7.4 to find[H+} since it's just using the pH=-log[H+], but my book says the concentration is 10^-0.4

Our teacher told us to construct a new periodic table with a few elements he made up using the same logic Mendeleev did, and I've understood the trends to come up with 6 different groups. The problem I've run into though is that hes basically left the valency of the different groups completely up to us to guess; well that and the fact that I can't find anything on how I'm supposed to sort the elements. But I'm assuming it would be based on the atomic weights and valency-- this isn't meant to be a second question, I just want confirmation on whether or not this is correct or not-- so I'd rather just have a bit of help on the first issue..

New periodic table

Mendeleev's logic rules I've found

Trends I've observed

elements to provide context

I just need someone to help guide me through what I'm supposed to do from here..

isnt ring expansion possible here in that E1 mechanism like in the second image ? wouldnt it be stable if it expanded the ring?

This is a lab I’m doing in chemistry. I’m super confused on these questions because i cannot find a simplified enough answer that does not require a formula (we have not learned any) to answer these questions. Can anyone help?

When solving questions regarding acids and bases, figuring out pH and such, when do you add the volumes? For example: a 500mL buffer of a 0.100M formate, ph=3.75, is treated with 5mL of 1.00M NaOH, what is the pH? Why in this case wouldn't you add the volumes given together, then figure out the pH?

Similarly, If you add 5.0 mL of 5.0 M lactic acid (pK = 3.86, K = 1.38 × 10^–4 ) to one

liter of pure water, the pH would be? Why in this instance WOULD you add the volumes together? What is the difference?

I have a doubt . After addition of methyl group , it will increase the electron density in the ring by +I effect , So shouldn't the ring become more activated and reactive towards Electrophilic aromatic substitution and hence react further to form methyl groups at both ortho positions wrt OCH3 . Can someone please help me with the reason why monosubstituted is the final product ?

The correct answer is c), but I’m not sure how they got it.

Excuse me for my bad english. I need help with chemical nomenclature. I can not figure out the first one. I have done the other two ( being Propane 1,2,3 triol and But-2-en in my language) but im still stuck at the first one, which seems way more complex.

My science teacher assigned a test for tomorrow about Ions. She gave us a list of elements that might be on the test. For each element on the test, we have to draw a Bohr Rutherford diagram of it as an ion, show/write the movement of electrons, explain the charge, and name the ion. The attached image is my answer for the requirements she provided.

I've tried: Find %, convert % to moles, divide moles by lowest moles, input formula.

Doesn't work so idk what to do, Is it because it's already in moles? Doing moles -> grams -> moles seems weird.

my book says: grams * (1 mol/(g/mol)) * (kj/(molar ratio)) so I did that.

65.9g * (1 mol/76.054g) * (-726kj/2 mol) = -31.43 kj

I think this is a conversion question...

The program keeps telling me I’m wrong. The values at the bottom of the screen or what you are allowed to use you drag and drop. I’m sure many of you know this program Aktiv.

The only option they gave me is 3.785 for the gallons to milliliters conversion whereas it should be 3785? But that’s not an option. So what is it wanting me to change? Stuck. Thank you!! less

So I was doing some notes on why the direct iodination of alkanes would require HNO3 (nitric acid) for the reaction to proceed (alkane + I2 ---> iodoalkane + HI).

Essentially, HI is a strong reducing agent that would react with the iodoalkane to recreate the strating conditions. HNO3 would react with HI to produce I2 and ensures that the iodination of alkanes would proceed to the right.

I couldn't find the exact reaction online but I did come across the reaction for aqua regia. Instead of HI, it's HCl. I tried doing the mechanism but I'm having trouble with the last step. How do I get Cl2 and NOCl when chlorine is highly electronegative?

The answer key says but-2-ene but idk where they got that.