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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Stability of Mercaptoundecanoic acid and thiol-PEG stored as solids

I am planning to use Mercaptoundecanoic acid (MUA, 98%) and thiol-PEG (O-[2-(3-Mercaptopropionylamino)ethyl]-O′-methylpolyethylene glycol) for functionalisation of gold nanoparticles. The SDS ...
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1 answer
50 views

What happens when we react a sulfate salt solution with barium chloride and the formed precipitate with conc. hydrochloric acid?

When I performed this experiment in my school, I could not observe any sort of remarkable change (I must have performed it incorrectly or something). I wanted to know what should have been the correct ...
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47 views

How to prepare standard sample of benzene for gas sampling bag?

I need to make a 1 ppm gaseous standard of benzene in nitrogen gas within a Tedlar® gas sampling bag. Is this as simple as injecting 1 μL of neat benzene liquid into 1 L of nitrogen gas within the bag?...
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1 vote
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60 views

Reaction Workup and Quenching

In the supporting information of synthetic paper by Buchwald's group, They use 2-MeTHF as solvent (See B. General Procedures for Amination part, page 8). After the reaction ends and cools the mixture ...
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What is the product of the following reaction(different sources give different answers) [closed]

$$\ce{FeS +dil HNO3}$$ $$\ce{FeS +conc HNO3}$$ I got different answers to these reactions in different sources Source1 Jd lee: Source 2 Op Tandon: Can anyone please explain which is the correct one ...
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1 vote
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41 views

How does the temperature of HCl affect the reaction rate of HCl & Mg reaction?

I'm Olivia. I'm experimenting with HCl and Mg. My purpose is to find the change of the reaction rate while I increase the temperature of HCi. According to the study, when I increase the temperature of ...
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3 votes
1 answer
131 views

Interpretation of permanganate-stained TLC spots

When I stain TLC spots with $\ce{KMnO4}$, I found that some spots appear differently as time goes by. Here is the example: The leftmost one is the plate right after staining, and the others are ...
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Using NaCl to change the relative humidity in the humidity chamber [duplicate]

The saturated NaCl will give around 75% RH in various temperature. Is there a way to use different concentration of NaCl in the water to generate different values of RH, i.e., 10% to 90% in the ...
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How are the energies of, e.g. the 4p orbitals of the first transition series, determined?

Take a first row transition metal, say manganese. The 4s and 3d orbitals are occupied in Mn; each orbital's energy can can be definitely determined by ionising that orbital, obtaining the resulting Mn+...
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1 vote
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Mass spectra interpretation for monitoring Buchwald–Hartwig coupling

I am conducting a synthesis involving Buchwald-Hartwig coupling. The starting materials are 2,3,5-tribromothiophene (MW=320.83) and 1-aza-18-crown-6 (MW=263.33). I used $\ce{Pd_2(dba)_3}$ (MW=915.7) ...
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1 answer
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What would happen to the cell potential if two half cells of a galvanic cell were at different temperatures?

I'm doing an experiment where I'm investigating the effect of temperature of the galvanic cell on the cell potential. But during the experiment, I noticed that the two half cells were at different ...
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For Radiochemistry why is a recovery range of 30-110% acceptable for isotopic tracers used for alpha spectrometry analysis of radionuclides?

Just like the title says. I am right now isolating and concentrating several radionuclides from environmental samples using micro-coprecipitation to be able to analyze it on an a alpha spectrometer. ...
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1 vote
1 answer
67 views

In electrolysis, can conductivity be used to predict current?

Since conductivity is the reciprocal of resistivity, it can be used to calculate resistance in the following equation: $$R=\frac{\rho l}{A}$$ $$R=\frac{l}{\kappa A}$$ Could this, along with Ohm's Law ...
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1 vote
1 answer
77 views

Water vapor permeation to the reaction flask

I am conducting a synthesis involving Buchwald-Hartwig coupling. The scale is $\approx10^{-4}$ mols of reagents. After running the reaction at 80 ℃ during 24 hours I found that sealing between the 3-...
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1 answer
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What is a better method when finding the iron content in spinach: Using titration or a spectrometer?

For my chemistry experiment, I want to boil spinach in water for different timings. Using the water that is left after boiling it, I was to determine the amount of iron content in the water solution. ...
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0 answers
34 views

What is 'pretreated carbon cloth substrate'?

I was reading this paper and found the following part of the working-electrode fabrication step: To prepare the working electrode, 4.0 mg of the catalyst or $\ce{IrO2}$ was dissolved in a mixed ...
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1 answer
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Experimental setup

I would like to know your opinion regarding the setup of a system for oxygen purging with nitrogen. Before ordering the necessary materials, I'd like to be sure if this setup is feasible or if it can ...
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-1 votes
3 answers
73 views

How to get tin(II) oxide from tin(IV) oxide? [closed]

How to get $\ce{SnO}$ from the deposited $\ce{SnO2}$? Any method is ok. If just heat the $\ce{SnO2}$, can it change to $\ce{SnO}$?
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0 votes
1 answer
136 views

Impurities in household baking soda

For a long time, I have been using store bought baking soda (with sodium bicarbonate as the sole ingredient listed) as the sodium bicarbonate in my (qualitative) home experiments, but recently I ...
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What readout techniques are used for dynamic combinatorial chemistry in drug discovery?

I am reading about dynamic combinatorial chemistry in the context of drug discovery. I am finding a frustrating lack of discussion in the literature about the methods used to extract useful ...
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Experimental difficulty with calculating reaction rates from multiple trials

Hi I' currently doing a chemistry experiment for school. I'm finding the pattern of reaction rate as temperature rises. My reaction is H2O2 + MnO2 and it produces O2 gas. I measured the volume of gas ...
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-1 votes
1 answer
80 views

How to determine the amount of CO2 sodium hydroxide absorbs?

I first created a solution of $\ce{NaOH}$ and water, 5g of $\ce{NaOH}$, and 100ml of water, with a pH of around 14. I then added $\ce{CO2}$ (mixing baking soda, citric acid, and water) to the solution....
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1 vote
0 answers
41 views

Relative Humidity inside a thermally insulated chamber for a NACL solution

I ran an experiment, where I had to measure the relative humidity of a thermally insulated chamber containing NaCl solution. I have read from a few papers, that the relative humidity of a NaCl ...
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3 votes
1 answer
187 views

How should you report measurements and uncertainty for a measuring cylinder with 0.5 mL graduations?

I understand that a common convention is to report the uncertainty of an analogue instrument as plus or minus half of the smallest scale division. By this logic, a measuring cylinder with $\pu{0.5 mL}$...
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-2 votes
1 answer
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Can anyone identify this instrument part and what instrument it comes from?

Can anyone identify this instrument part and what instrument it comes from?
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0 answers
39 views

How did we find relative atomic masses in 18th century or early 19th century? [duplicate]

The atomic masses of atoms or relative atomic masses were known in the 19th century. But how did they actually calculate that relative atomic mass? What I think is that if we have a sample of an ...
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2 votes
1 answer
76 views

What are the hydrodynamics behind a Soxhlet extractor?

So I'm trying to wrap my head around the physics of how a Soxhlet extractor works, not the chemical, solvent and chemical components part, but rather the physical, hydrodynamic, siphoning part : why ...
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5 votes
1 answer
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Can I use the Winkler method as a way to measure the rate of photosynthesis?

I want to make an investigation where I measure how the color of light affects the rate of photosynthesis. The idea is to put an Elodea plant in a test tube and shine with different color of light ...
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0 answers
25 views

Values of Hammett Acidity function for differing concentrations of H2SO4?

I am styling the effect of the concentration of different catalysts on the hydrolysis of sucrose to study it's reaction mechanism. I will be using the Hammett-Zucker hypothesis to find the ...
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0 answers
39 views

Glass fritted filter

Today I soaked my glass fritted filter with sulfuric acid 95% diluted 3 times. After many hours I wanted to check it but I found that the glass layer turned to grey or light blue color! I want to know ...
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4 votes
0 answers
80 views

Briggs-Rauscher reaction doesn't oscillate and turns blue with Vitamin C

I tried to recreate the Briggs-Rauscher reaction by using a solution of $\ce{H2O2}$, $\ce{KIO3}$, $\ce{H2SO4}$, $\ce{CH2(COOH)2}$, $\ce{MnSO4}$ and a soluble starch. I used this recipe. In container ...
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0 votes
1 answer
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Why are the relative masses of isotopes not close to whole numbers?

Understandably, the relative atomic masses of isotopes are often not close to whole numbers as they're adjusted for isotope abudandancy eg. $A_r(Cl)\approx35.45$. However, wouldn't one expect the ...
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5 votes
0 answers
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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{...
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1 vote
1 answer
69 views

Continuous variable for graph of boiling point of different chain lengths

Looking at the boiling points of alkanes (for examples), many graphs plot boiling point against chain length : However, there is an issue with the line of best fit- since chain length is a discrete ...
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2 votes
1 answer
65 views

Is it okay to use indicator as a powder instead as a solution in titration experiments?

My experiment involves titrating iodine solution against some sample solutions to find the amount of ascorbic acid in it. The indicator I'm using is 0.5% starch solution which will turn the solution ...
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1 vote
0 answers
84 views

Is there a way to calculate the rate constant of electrochemical cells?

I'm doing an experiment on temperature's influence on electrolysis of iron oxides and I need a way of measuring rate, preferably rate constant (k) or something similar. I've done some googling and ...
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What is the protocol for esterification reaction between nanocellulose and tartaric acid?

I am trying to prepare nanocellulose esters via esterification with Tartaric acid. I know that the traditional method employs a strong acid such as sulfuric acid. What would the process look like in ...
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-1 votes
1 answer
35 views

Will concentration of sodium hydroxide affect the result of chicken feather hydrolyzate if i don't standardized it?

The title of the paper: Isolation and characterization of keratin from chicken feathers https://doi.org/10.1063/5.0002792 Here is the method: Keratin was isolated by dissolving 5g of chicken feather ...
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19 votes
2 answers
2k views

Why is carbonic acid often ignored?

Water (distilled or not) picks up CO2 from the atmosphere, some of which dissolves to form carbonic acid (H2CO3), lowering the pH by a point or two. From that it seems like carbonic acid would be the ...
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1 vote
1 answer
181 views

Can ferrous ions exist in an acidic solution?

Can Fe2+ ions exist in an acidic solution or will they always pick up available protons and become Fe3+? My hunch is they can't exist but I'm not really sure. If the latter, does that mean that ...
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6 votes
1 answer
404 views

Fluorine detection in organic compounds

Many of you will know why I am asking this question. There is a lot of attention recently to the dangers of the so called Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS). In essence organic ...
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-1 votes
1 answer
35 views

Where does Aluminum Hydroxide come from in a reduction of a ketone by LAH? [closed]

The experiment was done in a Laboratory. A ketone was reduced with LAH in THF under reflux. At the end of the reaction, the protocol stated to add water until there is no more H2 released. The H2 ...
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0 votes
0 answers
25 views

Representing units for concentration of a liquid (v/v)%

I'm doing an experiment which involves testing a particular solution in different concentrations. Since this is a liquid, the concentration should be represented in v/v % rather than w/v %. However, I'...
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2 votes
1 answer
247 views

What is the "frequency of occurrence" referring to in this paper?

In Zhou et al.(2018) 22. 10.1016/j.geoderma.2018.02.015, table 1 of the different microplastics refer to a "frequency of occurence". Why does the % frequency of occurrence add up to >100%...
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1 vote
1 answer
120 views

What is the function of thin layer in thin layer chromatography?

I just learned about the thin layer chromatography, which I think is basically the same as the paper chromatography. I am wondering what is the function of the thin layer? I mean, what's special about ...
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0 answers
15 views

DI water vs. Tap water in ethanol-water and salt phase change reaction

We did a very simple lab like one you would do in highschool showing that you can seperate the phases of water and ethanol using salt. As simple as it sounds, we could not get it to work no matter ...
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0 votes
2 answers
78 views

What might cause overestimated measured pH value of sodium hydroxide solution pumped with carbon dioxide?

I tried an experiment at home where I had a $\ce{CO2}$ tank pumping $\ce{CO2}$ into a solution of $\pu{28 g}$ sodium hydroxide in $\pu{200 ml}$ water. The initial $\mathrm{pH}$ was $11.24.$ I expected ...
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0 votes
1 answer
50 views

How to apply a certain voltage vs SHE

For one of my projects, I must apply a voltage at the electrodes of -1V and +2V vs SHE. But my device potentiostat picks a voltages of 3V. How am i certain that it doesn't apply the voltage between -...
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1 vote
0 answers
27 views

How long do temporary dipoles last? [closed]

Theoretically, if you put 2 neutral atoms/compounds together in a controlled space with no external electrical fields, would a temporary dipole last forever, or would the jumping of electrons break ...
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-3 votes
1 answer
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The meaning of USFDA (in cosmetics) [closed]

The full meaning of USFDA base on the definition of cosmetic meaning and production
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