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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9
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1answer
729 views

Belousov-Zhabotinsky reaction: questions about rate determining step, k and activation energy

In one of our lab courses, we performed a variation of the BZ reaction, the experimental procedure is outlined below: Experimental Procedure 10 mL of 3.0 M $\ce{H2SO4}$ was added to test tube T1. ...
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6answers
4k views

A quick method for separating liquids?

I'm looking for a way to take 3 separate liquids (liquids which function as paint -- they will all be different colors), put them together into a container, and then rapidly separate them back to ...
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0answers
168 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/...
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0answers
824 views

Can I make Ferrofluid without evaporating Ammonium?

I want to make ferrofluid, which is ferromagnetic particles suspended in a carrier fluid. Three methods I have seen involve using magnetic ink (for MICR codes), cassette tapes, or ferric chloride as ...
9
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0answers
188 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 ...
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4answers
15k views

How do I control the negative temperature in an experiment?

If one were to adjust the positive temperature in an experiment, they would use a heating plate, or a stovetop. How would one adjust negative temperatures in an experiment? (Not keeping the ...
8
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1answer
2k views

What would be the effect of adding liquid beyond the calibration mark on a volumetric flask?

If this happens in the course of preparing a volumetric solution, what should be done?
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2answers
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Can we recycle garbage with the principles of mass spectrometry?

'Mass Spectrometry (MS) is an analytical technique that sorts ions based on their mass (or "weight"). Mass spectrometry is used for many chemical analyses, ranging from the analysis of a complex ...
8
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1answer
4k views

What does "lit." mean in boiling point or melting point specification?

For example, this Xanthene 99% specification from Sigma Aldrich states: \begin{array} \\\hline \text{bp} & 310-312 ~^\circ\mathrm{C~ (lit.)} \\\hline \text{mp} & 101-102 ~^\circ\mathrm{C~ (...
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1answer
12k views

Why are lab coats required in chemical laboratories?

Well at first it seems kind of awkward but let me tell you what I was thinking from past few days. Currently I am studying and go to school. In school, whenever we have to go inside a chemistry lab ...
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2answers
25k views

Why are strong acids and bases not suitable as primary standards?

This is one of the questions with which I have puzzled over, and can arrive at no definite conclusion. Why are strong acids or bases, such as $\ce{H2SO4}$,$\ce{ HNO3}$, $\ce{HCl}$, and $\ce{NaOH}$ not ...
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2answers
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How to tell between carbon powder or graphite powder?

I have a black powder that I cannot reliably tell just by looking or touching whether it is graphite powder or charcoal powder. Are there any simple tests that I can perform to tell whether it is one ...
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1answer
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What effect does hydrogen bonding have on H NMR spectra?

My thinking is that an increase in electron density caused by hydrogen bonding should cause the chemical shift of participating atoms to be moved downfield. Am I right or wrong? Can someone provide ...
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1answer
2k views

Does excessive sulfuric acid as catalyst affect the synthesis of aspirin? [duplicate]

Recently had a lab experiment to synthesize aspirin. I was instructed to add 4 drops of concentrated sulfuric acid but misread the "4 drops" as "4 ml". Ended up with a yield of just 10 %. But the ...
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1answer
2k views

How does the Mentos-Coke explosion work?

We all might have seen this in some videos or in real life. But how exactly does this work? What is the chemical reaction involved? And why is the reaction of Mentos with Diet Coke more vigorous? ...
8
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1answer
191 views

How to characterize gaseous ethylene that forms as byproduct?

I'm running a reaction that has ethylene gas as a byproduct. I have observed gas evolution as my reaction proceeded and I have other ways of verifying the identity of the main product, but I thought ...
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2answers
3k views

Why is the photon energy of lithium flame coloring lower than that of cesium?

Why does $\ce{Li}$ give a red flame color which has lower photon energy compared to $\ce{Cs}$ which gives a violet flame color according to $E=h\nu$? This is my attempt: Since lithium has smaller ...
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1answer
1k views

Vacuum distillation apparatus selection and configuration

I want to assemble a "hobbyist-level" vacuum distillation apparatus for extracting small volumes of "typical" solvents (e.g., water, alcohols, ketones, diols). I already have standard lab glassware ...
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2answers
5k views

What is the real pKa of water?

What is the $\text{p}K_\text{a}$ of water? A simple google search yields the value $15.74$, but this site and this paper say it's $14.0$. According to my understanding, the correct answer should be $...
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1answer
5k views

What is a baseline?

I am currently doing a lab write up for biology, in which the purpose of the lab is to "Develop a Method for Measuring Peroxidase in Plant Material, and to Determine a Baseline." This is supposed to ...
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4answers
2k views

Smith Hieftje correction method

I completely don't understand how this method works. My book says that this method works by the principle of self-absorption which occurs by the emitted radiation of hollow cathode lamp when it works ...
8
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2answers
453 views

How to translate the mobile phase from thin layer chromatography to column?

I recently was told that once you find a good solvent mixture for separation on thin layer chromatography (TLC), you should only use 10% of the more polar solvent (for silica) when you run your column....
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2answers
15k views

Can ethanol be oxidized by hydrogen peroxide?

Is it possible to oxidize ethanol to acetic acid with hydrogen peroxide and if yes then under what circumstances? I tried it in room temperature but either concentration was too small (of hydrogen ...
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1answer
5k views

Plotting a Langmuir adsorption isotherm

We have, $$\theta = \frac{Kp_\mathrm a}{1+Kp_\mathrm a}$$ where, the fractional coverage $\theta$ is defined as the number of sites occupied by adsorbate $A$ over the total number of sites. $p_\...
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1answer
115 views

Continuous flow mass spectrometer for isotope analysis

If i took thousands of discrete samples of mineral fragments in a field study using a specialized drill, what mass-spectrometry techniques/equipment would allow me to analyse the samples as fast as ...
8
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1answer
211 views

Organic solutions that corrode metals

Most of the common organic solvents are regarded as noncorrosive, but stainless steel can be attacked by formic, acetic, and propanoic acids. Corrosion of stainless steel by organic solvent mixtures, ...
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0answers
928 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 ...
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0answers
946 views

What is the fabric in heating mantles made of?

An ordinary lab heating mantle often has a white fabric coating for the flask compartment, which looks like an inorganic fiber: Image source I'm pretty sure that for some time in the past ...
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1answer
607 views

How would you measure the rate of this SN1 reaction?

I am performing the following $\mathrm{S_N1}$ reaction: $$\ce{t-BuOH + HCl -> t-BuCl + H2O}$$ I would also like to measure the rate of this reaction, but I cannot seem to find a way. I initially ...
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1answer
102 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 ...
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8answers
23k views

Is there a simple and inexpensive way to generate nitrogen gas?

It's fairly easy to generate a significant yield of hydrogen gas simply by reacting zinc metal with $\ce{HCl}$ or aluminum with $\ce{NaOH}$ solution. But is there a simple and inexpensive chemical ...
7
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3answers
431 views

Choosing reaction stoichiometry in organic synthesis

Reading papers about organic synthesis, I see many cases like setting one material as 1.2 eq. I presume that reagents used more than 1 equiv are relatively inexpensive or less reactive than other ...
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2answers
1k views

Why does ethylamine have two infra-red spectra? Are both correct?

The one I have in my textbook is this: Shouldn't the first trough at $3500$ to around $3000$ mean that it's an $\ce{O—H}$ group with a $\ce{C—H}$? And then the other trough at $1700$ be a $\ce{C=O}$? ...
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3answers
2k views

Zero filling leading to increases in resolution (NMR)

Zero-filling involves adding data points with zero intensity to the end of an FID. According to this website https://www2.chemistry.msu.edu/facilities/nmr/handouts/DH%20NMR%20Basics.pdf zero filling ...
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3answers
2k views

How much salt (or any other substance one can find in a kitchen) do I need to add to make water boil at 104 °C?

I've seen some formulas around in other questions and Google searches, but my chemistry is pretty much dead so I have no clue where to find the relevant values to calculate it myself. I just need to ...
7
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4answers
584 views

What's the purpose of significant figures in measurements?

I have read about significant figures in my chemistry and physics books, but none of them pointed out the significance of the significant figures. Searching the Internet I found two possible answers: ...
7
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1answer
6k views

Concentration of NaOH to dissolve glass

I am doing a physics experiment in which it is required to etch the outermost glass layer from a coverslip (regular lab apparatus). What concentration of NaOH should be dissolved in water, and how ...
7
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3answers
9k views

Is there a way to experimentally measure entropy?

I've been doing thermodynamic chemistry, and recently focusing on Gibbs Free Energy. Whilst doing calculations using, $$\Delta G = \Delta H - T \Delta S$$ I have been given a table of values for $\...
7
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2answers
5k views

How long does it take to run an MS/MS experiment

I am not planning to do these types of experiments but I would like to know the order of magnitude of the time it takes to run an LC-MS/MS experiment. Let's assume that I have the sample prep (protein)...
7
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1answer
294 views

What's the reaction here?

I have found a gif photo on the internet and I am very curious what is happening there? What reaction is the reason for that?
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2answers
1k views

Storing large quantities of KOH

I need to handle large quantities of $\ce{KOH}$; close to 1000 liters of 85 % conc $\ce{KOH}$ for about an hour. Any suggestions on how I go about doing it? Also the temperature during the process ...
7
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1answer
3k views

Why must NaOH be kept dry during storage?

Why should the Erlenmeyer flask used to store $\ce{NaOH}$ be dry? Why should it be kept covered at all times?
7
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4answers
27k views

Why do they use graphite electrodes in the Hall–Héroult process?

In the Hall–Héroult process of extracting aluminium from aluminium oxide, the electrolyte is a liquid mixture of cryolite $(\ce{NaAlF6})$ and aluminium oxide $(\ce{Al2O3}).$ The cathodes and the ...
7
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1answer
28k views

diH2O, dH2O, and DI H2O. What do they mean?

What do $\ce{diH_2O, dH_2O}$, and $\ce{DI H_2O}$ mean? I'm not asking for a description of deionized water and distilled water. I'm asking what the three abbreviations/formulas mean. In other words, ...
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1answer
1k views

Is it possible to chemically treat grass to make it digestible?

Is it possible to chemically treat grass after "harvesting" it to make it digestible by humans? I know we can "eat" grass, but we can't break it down in our stomachs. If there is some chemical ...
7
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1answer
772 views

What is the purpose of trimming the bottom corners of TLC plates?

During my chemistry lab course, I was told by my instructor to make 2 small cuts on the bottom corners of the TLC (Thin-Layer Chromatography) plate. Does this make the solvent rise uniformly on the ...
7
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2answers
5k views

Removal of tetrabutylammonium from an organic reaction

I need to synthesize some organic compound for my Ph.D. research. Everything went OK during the synthetic route but got messed up at the very end. In my final step (once the final compound has been ...
7
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1answer
6k views

Best Fuel for Potato Gun

I have been using deodorant to propel potatoes (potato gun :D), but I want to switch over to pure butane. However, in order to do this safely I have to know how much butane is typically in deodorant (...
7
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1answer
930 views

Why does thallium hydroxide increase the yield of product in a Suzuki reaction?

I came across a research paper by Uenishi et al. [1] where relative rates of $\ce{KOH}$ and $\ce{TlOH}$ in Suzuki coupling reactions are compared. Thallium hydroxide increased the yield of products, ...
7
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1answer
8k views

How many decimal places should a volume measurement in a beaker include?

I have a beaker which goes up in $0.5~\mathrm{mL}$ increments and my teacher told me that my measurement $(15.50~\mathrm{mL})$ was incorrect, and instead the answer was $15.5~\mathrm{mL}$. I don't ...

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