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Questions tagged [experimental-chemistry]

This tag should be applied to questions relating to the theory, design, techniques or performance of chemical experiments. This includes but is not limited to theoretical structures, expected products, thermal calculations, and empirical analysis. Additional tags should be applied to narrow down the field of research.

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23 votes
1 answer
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What is Q-carbon? Does it exist?

Glowing press releases and news articles in 2015 proclaimed a new allotrope of carbon. However, even the journal article is light on chemical detail (e.g. no structural formula). What is its bond ...
Foo Bar's user avatar
  • 440
14 votes
1 answer
7k views

Why do alpha-hydroxy ketones respond positively to Tollens', Fehling's, Benedict's, Schiff's and HgCl2 tests?

I learnt from a certain textbook that aldehydes and formic acid respond positively to Tollens', Fehling's, Benedict's, Schiff's and HgCl2 tests. However, in another textbook I read that even alpha-...
user avatar
12 votes
0 answers
1k views

Role of pH in azo C-coupling reaction, continued

In the question, "What is the role of pH in azo coupling reaction of diazonium with phenol and aniline?" asked by @DhrubaBanerjee and answered by @Klaus-DieterWarzecha, I find several ends ...
William R. Ebenezer's user avatar
12 votes
0 answers
92 views

Is there a structured data source containing information on the World Health Organisation's Stability Testing Policies?

Hoping to automate some product testing guidance software, I've been attempting to find a (hopefully live, up-to-date) Database, Web-service, or other structured data source containing the ...
user32052's user avatar
  • 121
10 votes
0 answers
213 views

How to get defect-energy level diagram from PL data

I am reading this article Phys. Chem. Chem. Phys. , 2011, 13, 14902-14905 and seen that the authors have drawn a image of defect level using PL data Can you explain me how this diagram can be drawn ...
Eka's user avatar
  • 2,768
9 votes
0 answers
257 views

Quantitative Transfer of Volatile Standards

(Edited w/ updates) Okay, long story short I work in a lab which has been working on cannabinoid analysis (in the licensed Canadian market) and have had a lot of issues surrounding the standards/...
Donald Bowins's user avatar
9 votes
1 answer
114 views

Will the sulfur-iodine cycle and Haber Method work at lower pressures and temperatures?

I have a year-long research project next year in my senior year of high school, in which we have to make some product or prototype to solve some issue. My interest was in the Liquid Fluoride ...
user116160's user avatar
8 votes
0 answers
2k views

Tables/database/literature of specific or optical rotation

I'm looking for a comprehensive reference of experimental specific rotation or optical rotation data. It can be a published literature review, a free web database with API access or one that permits ...
pentavalentcarbon's user avatar
7 votes
0 answers
197 views

Distilling milligram quantities of oil like it's late 1970s

In a currently retracted* manuscript by Tomas Hudlicky [1, Retraction Watch] the following has been noted: Fifty years ago professors took an active part in all laboratory instructions and they ...
andselisk's user avatar
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7 votes
0 answers
515 views

Does phosphoric acid remove stainless steel electropolished layer?

Electropolished stainless steel has a high corrosion resistance due to the oxide film that is created during electropolishing. The film mainly consist of chromium(III) oxide. Phosphoric acid is ...
Jaroslav Kotowski's user avatar
7 votes
0 answers
65 views

Linear PEI Solution Making

I'm making a solution with linear poly(ethyleneimine) $\ce{[CH2CH2NH]_{n}}$. The bottle indicates that the substance is hygroscopic and must be dealt with under inert gas. Is this really necessary? ...
Danielle's user avatar
6 votes
0 answers
77 views

How well the conclusion from the "Ignition!" book on rocket fuel science stood the test of time?

There was a wonderful book called "Ignition!" by John D. Clark, published around 1972, very interesting to read. That book covers the history of the rocket fuel development in the middle of ...
hijarian's user avatar
  • 291
6 votes
0 answers
2k views

Finding theoretical mechanism of sodium thiosulphate and hydrochloric acid

In class we conducted an experiment where we timed reactions between sodium thiosulphate and hydrochloric acid. We kept the concentration of the $\ce{HCl}$ constant, while changing the concentrations ...
2247382's user avatar
  • 69
5 votes
0 answers
43 views

Why cool a reaction down when adding reagents if you're only going to reflux subsequently?

I've seen several procedures using thionyl chloride (SOCl2) to make an ester, where the first step is to add the thionyl chloride to the reagent/solvent on ice or subzero temperature, followed ...
sat0ri's user avatar
  • 171
5 votes
0 answers
77 views

Oxygen tolerant RAFT polymerization using AIBN?

I want to do some RAFT polymerizations but don't have a nitrogen line at the moment. It seems that people have recently implemented oxygen scavenging strategies to enable open-air RAFT polymerization. ...
toodles's user avatar
  • 137
5 votes
1 answer
64 views

How to make a thin layer of crystalline barium titanate on copper substrate?

Is it possible to create a thin $\ce{BaTiO3}$ crystal layer on a copper plate by putting the plate in a beaker, pouring in heated hydrofluoric acid that has been saturated with $\ce{BaTiO3}$ powder ...
Martin Kontsek's user avatar
5 votes
0 answers
62 views

How to experimentally determine the dissociation energy (electronegativity) between identical atoms?

I was reading on Wikipedia about how Pauling electronegativities are determined through $$ \vert \chi_\ce{A} - \chi_\ce{B} \vert = \sqrt{E_\mathrm{d}(\ce{AB}) - \frac{E_\mathrm{d}(\ce{AA}) + E_\mathrm{...
Hale Bays's user avatar
5 votes
2 answers
168 views

Should I add more of a trihydrate chemical to a solution if recipe calls for hemihydrate?

I am running phosphate by the ascorbic acid method (SM 4500-PE, PDF), and making the antimony potassium tartrate reagent. Standard methods uses $\pu{1.3715 g}$ of $\ce{K(SbO)C4H4O6 * 1/2 H2O}$ per $\...
H3vyM3741's user avatar
  • 111
5 votes
0 answers
1k views

Why are NBr3 and NI3 unstable, but NF3 is stable?

Why are NBr3 and NI3 unstable, but NF3 is stable? Is there any reasoning behind the stability? I found that one nitrogen can accommodate fluorine easily, but not the others. Also, I don't understand ...
user39914's user avatar
5 votes
0 answers
5k views

Should I round an experimentally determined reaction order to an integer?

For a lab experiment I did, I calculated the reaction order for one of the reactants using data from two trials, both rates, and the concentration of that reactant during each. $$ \frac{\text{Rate}_1}{...
Caesium-133's user avatar
5 votes
0 answers
303 views

Reduction of vanadyl ion

I want to reduce vanadyl to vanadium (III), can somebody please suggest some appropriate methods for it? I am trying to make a redox flow battery for a project but I have only vanadyl sulfate.
Akarsh's user avatar
  • 59
4 votes
0 answers
45 views

Largest molecules verified in a Miller Urey experiment

What are the largest molecules confirmed with confidence in a Miller Urey experiment? I know the experiment can create amino acids (which are mostly <250Da) and nucleotides (which are mostly <...
fireworksparkle's user avatar
4 votes
0 answers
86 views

Why is Fe-P in NaOH part of Hieltjes & Lijklema (1980) P fractionation?

Background: In order to separate the different phosphorus (P) species in lake or marine sediments, one can use sequential P fractionation method. Its main idea is to use extractants with weak or ...
T X's user avatar
  • 143
4 votes
0 answers
85 views

Notation for spectral density in experimental community

In an open quantum system setup where the system is coupled to infinite harmonic oscillators as bath (as in the Caldeira leggett model, for example), through the Hamiltonian, $$H = \frac{\hat{p}^2}{2m}...
Prem's user avatar
  • 91
4 votes
0 answers
184 views

Does acrolein give positive iodoform test?

Which of the following compound(s) give(s) a positive iodoform test? A. Acrolein B. Acetone C. Acetoacetic ester D. 2-Propanol According to me, the answer should be options B, C, and D as B is a ...
Vyom Joshi's user avatar
4 votes
0 answers
1k views

Why is the Suzuki coupling done under inert atmosphere?

There are plenty of sources saying that the Suzuki coupling is air-sensitive (even though there are some versions that require oxygen). However I'd like to know why a typical Suzuki coupling is air-...
Dion Silverman's user avatar
4 votes
0 answers
597 views

Why does my drierite turn bright bright blue, instead of pink?

Drierite a brand name of a commonly-used, calcium sulfate-based dessicant in many chemistry labs. The lab I work in has a dessicator box we use to store hygroscopic materials. It isn't a a true dry ...
Curt F.'s user avatar
  • 21.9k
4 votes
0 answers
424 views

Why is the experimental pH of vinegar (acetic acid) so much higher than expected?

I bought some sodium hydroxide on Amazon and went about titrating solutions I make with it. As I'm an amateur chemist at home, I have limited tools. A pad of paper, some 5% acetic acid vinegar, and ...
Jonathan Allard's user avatar
4 votes
0 answers
61 views

membrane for a reverse osmosis desalination experiment

We are second year cram schoolers , we are currently working on a project tackling water desalination by reverse osmosis and are required to do an experience. During the process, we encountered some ...
moistandunstable's user avatar
4 votes
0 answers
82 views

An unknown glassware piece from our cupboard

We have multiple of these. It is a small glass funnel with splits into 3 spouts from it. Now, we are thinking it might be similar to a cow receiver, however, I have never seen one this small or ...
hreeve1's user avatar
  • 99
4 votes
0 answers
39 views

Unknown possibly handmade glassware- description in information below

Okay, Another random item from the cupboard (unknown users or discipline of life sciences unknown) could be anything up to 40 years old.... This appears to be a 2 neck quickfit adapter (B19 and B14) ...
hreeve1's user avatar
  • 99
4 votes
1 answer
692 views

Extrapolating from a calorimetry lab to find a new delta T with different volumes and grams of substance

So, we just finished an AP chem lab where the question was basically: Given the results of the lab were that $\pu{5 grams}$ of $\ce{CaCl2}$ and $\pu{45ml}$ of water produced a $\pu{13.33 ^\circ C}$ ...
catdog's user avatar
  • 49
4 votes
0 answers
2k views

Why Rutherford was shocked by results of gold foil experiment?

The way Rutherford's classic gold foil experiment has been presented (including by Rutherford himself) doesn't make sense to me. As many of you know, Rutherford famously described himself as being ...
theorist's user avatar
  • 12.2k
4 votes
0 answers
269 views

What is a good solvent for pentacene?

I am doing an experiment with pentacene molecule ($\ce{C22H14}$). I want to clean my sample reservoir after using it. But I show in some literature that it is slightly soluble in organic solvent. ...
saroj's user avatar
  • 41
4 votes
0 answers
291 views

Waterproofing and recycling paper

I've recently begun studying about waterproofing paper. Through what I learned is that the reason why paper absorbs water so easily is mainly because of it's material composition. Paper is generally ...
Czar Luc's user avatar
4 votes
0 answers
111 views

How can I test fruits and vegetables for certain insecticides?

I live in Turkey and I don't feel safe eating the fruits and vegetables that I enjoy that are plentiful here. After reading this article, I have been washing all fruits and vegetables with water and ...
0tyranny0poverty's user avatar
4 votes
0 answers
659 views

Why isn't my Cu2O Cuprous Oxide red

A thin film sample of polycrystalline Copper(I) Oxide (Cuprous Oxide, $\ce{Cu2O}$) on quartz looks reddish in the center but bluish/grayish on the sides where the film is thicker. The same thin film ...
Athena Wisdom's user avatar
4 votes
0 answers
176 views

Expedient phosponium synthesis (for Wittig)

I have been making ethyltriphenylphosphonium bromide (somewhat of a time crunch, would have used iodoethane instead of bromoethane if we didn't have to wait for it). All the syntheses I see of Wittig ...
SendersReagent's user avatar
4 votes
0 answers
960 views

Oxidation of dihydropyridine

This is a step in a experiment I have carried out. Usually DDQ (dichlorodicyanoquinone) would be used here to oxidise the dihydropyridine. However in this case Nitric Acid is being used as the ...
Petrichorr's user avatar
4 votes
0 answers
771 views

Experimentally proving the mechanism and rate laws of SN1 & SN2 reactions

I have been given the task of experimentally proving the rate laws and mechanisms of $\mathrm{S_N1}$ and $\mathrm{S_N2}$ reactions. Unfortunately, the only equipment I can use is limited to analytical ...
Saul McShane's user avatar
4 votes
0 answers
1k views

An alternate purification process for sugar separation form bee honey?

Bee honey contains 75% sugars (Fructose, Glucose, Maltose, Sucrose and others), some water and low amount of different compounds (up to 5%) Wiki. Basic purification is done by addition of phosphoric ...
Jaroslav Kotowski's user avatar
4 votes
0 answers
384 views

What causes the yellowing of the linear alkylbenzene (LAB) cocktail?

In our lab, we use the liquid linear alkylbenzene (LAB) cocktail mixed with 2g/L 2,5 diphe-nyloxazole (PPO) as the organic scintillator for radiation detection. The new LAB cocktails are stored in the ...
jwhoo's user avatar
  • 41
4 votes
0 answers
111 views

Synthesizing monodisperse PbS quantum dots

For a research project, I am trying to synthesize lead (II) sulfide quantum dots using the method of Li et al.. I am injecting sulfur dissolved in 1-octadecene into a mixture of $\ce{PbO}$, oleic ...
Albert's user avatar
  • 41
4 votes
1 answer
1k views

Fehling's solution turning yellow and then black?

While testing for formaldehyde (an aldehyde), I added Fehling's solution to the sample and let the test tube simmer in a water bath for some time. I returned ~15 minutes later to see a black/dark grey ...
Aniruddha Deb's user avatar
3 votes
0 answers
44 views

Calculate percent composition from XPS?

I have an XPS graph and was wondering how to calculate percent composition. I do have the percent compositions that were determined from the graph, but I don't know how they were found. For reference, ...
lzzard's user avatar
  • 39
3 votes
0 answers
39 views

Voltammogram during calibration is not smooth

During calibration for differential pulse voltammetry, the voltammogram obtained has two distinct peaks. I am not sure why I am getting two peaks in the range from $\pu{-0.6 V}$ to $\pu{-0.9 V}.$ I ...
AvG's user avatar
  • 31
3 votes
0 answers
54 views

Will bubbling nitric oxide through a solution of sodium percarbonate neutralize the NO?

The sciencemadness wiki page on Nitric Oxide (https://www.sciencemadness.org/smwiki/index.php/Nitric_oxide) states that NO can be neutralized by "bubbling it in a sodium percarbonate solution&...
fllw_inf_jst's user avatar
3 votes
0 answers
42 views

Reaction of BTNA, DMSO, and phosphate?

I prepared a solution of n-benzoyl L-tyrosine p-nitroanilide (BTNA) in dimethyl sulfoxide for use in an enzymatic assay. However, mixing it with a solution of phosphate buffer produced a color change ...
user73910's user avatar
  • 1,264
3 votes
0 answers
141 views

Why the change of the position of the salt bridge or metal piece leads to different voltage value?

I am doing an experiment where I use salt bridge to create galvanic cell. The goal of my experiment is to find if there is some correlation between the amount of solvent being used and the voltage ...
James's user avatar
  • 139
3 votes
0 answers
48 views

How to calculate composition of alcohol/water mixture to achieve given concentration of alcohol vapors in air for calibrating a DIY breathalyzer?

I made a breathalyzer using a MiCS-5524 gas sensor. I would like to calibrate it so it can be close to accurate. e2v technologies — MiCS Application Note 4, Using MiCS Sensors for Alcohol Detection (...
Bill2k's user avatar
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