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.
1,525
questions
-4
votes
0answers
14 views
How to calculate the temperature when equipartition is estimated [closed]
what must be the temperature be before the energy estimated from equipartition theorem is within 2 percent of the energy given.
please help me to solve this.
E= hcv/e^(bhcv)-1
v is the wavenumber is ...
0
votes
0answers
15 views
How to experimentally measure ground state energy of molecules [closed]
How can one calculate the ground state energy of a molecule (an energy corresponding to ground state Hamiltonian of molecule, theoretically speaking). Can you please explain.
Thank you.
-2
votes
0answers
15 views
How do I measure concentration of CO2 evolved from a decomposition reaction of a metal carbonate?
Context: I have to design and perform an experiment in school where I have to decompose various metal carbonates and measure the rate of reaction. I realise one way to do it is to measure the ...
-1
votes
1answer
57 views
Mixing hydrogen peroxide and sodium hydroxide doesn't lead to sodium peroxide anymore [closed]
I've been using same bottle of hydrogen peroxide and same bottle of 50 % of sodium hydroxide to make sodium peroxide for a month now. You could see the presence of sodium peroxide in the solution ...
-3
votes
0answers
18 views
what are the Materials required for the Biginelli reaction? [closed]
I am an IB student doing chemistry HL and for my IA I wanted to do the biginelli reaction but as I researched I found no information about the actual experiment I just wanted to ask if anyone knew ...
-1
votes
0answers
17 views
Tracer Recovery in Analysis of Alpha Emitting Radionuclides
I am doing experiments analyzing the activity concentrations (Bq/kg) of several radionuclides and there is a small thing I don't quite understand how tracers work in the calculation of the activity ...
-1
votes
0answers
38 views
Electrolytic Cell [closed]
I was wondering how the concentration of an electrolyte effects the metal production in an electrolyte? It would be great if could get a formula to represent impact of concentration on mass of metal ...
2
votes
0answers
23 views
Solvent choice in imine formation from quercetin and poly(allylamine)
I am trying to react quercetin and poly(allylamine) to form imine on the repeating units. Poly(allylamine) is dissolved in water. The problem is the choice of solvent. Poly(allylamine) is soluble in ...
-2
votes
0answers
38 views
Standard Enthalpy of formation
The definition says
The standard enthalpy of formation is defined as the change in enthalpy when one mole of a substance in the standard state (1 atm of pressure and 298.15 K) is formed from its pure ...
1
vote
0answers
28 views
Why is my Briggs-Rauscher reaction oscillating but failing to turn blue?
As the title says, I've constructed a Briggs-Rauscher reaction according to the ever-popular "Chemical Demonstration: A Handbook for Teachers of Chemistry" by B.Z. Shakhashiri (the same ...
0
votes
1answer
44 views
How is nitrogen gas passing through condensed water in the U-Tube while reducing metal oxides with ammonia gas?
In my school chemistry book, the experiment about the reduction of metal oxides with ammonia has a diagram of the set up as follows:
$$\ce{NH₃ + CuO → 3Cu + 3H₂O + N₂}$$
The tube entering the U-tube ...
1
vote
2answers
51 views
Just looking for some help with finding relative ratios of components in a mixture using proton NMR
G'day,
I am used to identifying molecular structure in isolation using proton and carbon NMR, but have never worked with a mixture before. The mixture relates to the following spectrum:
The spectra ...
0
votes
1answer
26 views
What would happen if I increase the pressure and temperature of a gas present in a container
Assume the gas to be a real gas and the container to be made of diamond or anything stronger than that. Take the amount of gas to be 2mL and the pressure is increased with the help of strongest ...
1
vote
1answer
55 views
Method to remove impurities from acetaminophen synthesis experiment
I'd like to know about impurities from acetaminophen synthesis experiment. Are there any impurities produced by oxidation of p-aminophenol? If there is any impurity produced by oxidation of p-...
0
votes
0answers
45 views
Best practices to obtain small quantity of sealed solution without oxidising entire solution?
I'm ordering liquid based chemicals which only come in large bulk quantities. These solutions have a shelf life of approximately 2 years unopened, but 2 - 3 weeks once opened and oxidation kicks in. ...
1
vote
0answers
33 views
How to prepare an emulsion (compounds in wt%)
I am trying to replicate an experiment to generate microparticles but I found myself confused about how to prepare the ingredients as some need to be weighed and dissolved before and I think the ...
1
vote
0answers
38 views
Differences in activated manganese dioxide synthesis
I've looked into preparations of activated manganese dioxide for some time now, and what confused me is the contrast between the original Attenborough method and some of the alternatives.
A solution ...
1
vote
1answer
58 views
NaOH + atmospheric CO2: Unexpected results troubleshooting
I've conducted an experiment where a solution of $\pu{4.2 M}$ $\ce{NaOH}$ was left exposed to atmospheric $\ce{CO2}$ for a period of time and titrated using potentiometric titration and potassium ...
2
votes
0answers
54 views
Analysis of reaction mixture by TLC and finding column chromatography condition
I am conducting an organic synthesis. Below is the TLC image.
I used dichloromethane:methanol:triethylamine=10:1:0.15 as eluent, but I stored it during 3 days, so it may be a little bit concentrated.
...
5
votes
2answers
87 views
Why do alkenes (olefins) burn hotter than alkanes (paraffins), even though alkanes are denser and more hydrogen-rich?
Burning hydrogen releases more total energy than combusting carbon, and all alkanes are denser as well, so why are flame temperatures for alkene molecules higher than their equivalent alkanes?
P.S.: ...
3
votes
1answer
78 views
Friedel–Crafts acylation of substituted anisole
I am attempting to form a synthetic route to a tetrasubstituted benzene compound. In the scheme, there is a step that requires the formation of a carbon–carbon bond in the C-6 position of a methoxy ...
6
votes
2answers
2k views
Which is a more accurate scale for a chemistry high school lab - a triple beam balance or a digital balance and why?
I would like to ask the experts of this chemistry community their opinions on which balance is more accurate and effective to use in a high school chemistry lab- a triple beam balance or a digital ...
7
votes
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 ...
3
votes
0answers
63 views
How can I store reagent under inert gas?
I need to store some aliquots of 2,3,5-tribromothiophene. I searched for how to store reagent under inert gas, And I found this : https://avantilipids.com/tech-support/faqs/protect-from-oxidation
In ...
1
vote
0answers
31 views
Problem about TLC solvent and staining
I am conducting an organic synthesis involving 1-aza-18-crown-6-ether. I tried TLC, but they didn't work well. I have tried: (1) hexane+ethyl acetate in various ratio, (2) dichloromethane:methanol=3:1,...
0
votes
0answers
23 views
Why does pure alpha glucose powder clump when attempting to dissolve in water and become very hard?
I noticed that when I attempted to dissolve some pure alpha glucose powder in water, it would become hard and clump at the bottom of the beaker if I dumped it into the beaker all at once. It was ...
-4
votes
1answer
53 views
How Bread is made with yeast, sugar and luke warm milk? [closed]
Materials and Apparatus:
wheat flour
sugar
dry yeast
glass bowl
covering plate
milk
Procedure:
Lukewarm milk is taken in the glass bowl and sugar is added to it. Then, yeast is added to the same.
...
0
votes
1answer
55 views
Setting up reactor in inert atmosphere
I am searching for reactor set-up that can maintain inert atmosphere, and found that many organic synthesis labs use Schlenk line. But organic synthesis is not main thing of my lab, so there is some ...
2
votes
0answers
62 views
How to do a capacitively coupled electrode?
I have an AUTOLAB potentiostat: working electrode (WE, Pt wire), counter electrode (CE, Pt wire), reference electrode (RE, Ag/AgCl solid state).
I would like to capacitively couple the potentiostat ...
3
votes
0answers
53 views
Purification of Buchwald-Hartwig amination
I am conducting a synthesis involving Buchwald-Hartwig amination. I use $\ce{Pd2(dba)3}$, $\ce{P(o-tol)3}$, and $\ce{Et3N}$ as base. In many proposed mechanisms, they often omit the precatalyst. I ...
4
votes
2answers
83 views
Should I do solvent extraction for Buchwald–Hartwig amination?
I am conducting a synthesis involving Buchwald–Hartwig amination. Catalyst is $\ce{Pd2(dba)3},$ ligand is $\ce{P(o-tol)3},$ base is $\ce{Et3N},$ and solvent is toluene. Image below is the proposed ...
-1
votes
1answer
49 views
How to thermally insulate beaker glass on hotplate?
I bought a magnetic stirrer with a hot plate almost identical to this one.
I am trying an experiment where I need to heat the beaker/mixture to about 100 degrees C. However the mixture/beaker is ...
1
vote
0answers
65 views
Is it possible to run column chromatography in reversed phase?
I'm conducting a synthesis involving aza-crown-ether.
Whether aza-crown-ether acts as a base or not is unclear, but when I do TLC using dichloromethane/methanol, it is hardly drawn up with the mobile ...
2
votes
0answers
29 views
In cation analysis, can reagents of higher group precipitate lower group cations?
My teacher told me that Al$^{3+}$ and Zn$^{2+}$ hydroxides are frequently precipitated together and that is why we have to be careful about the concentration of base (NH4OH) added.
Does this mean that ...
1
vote
0answers
55 views
Leakage during Celite filtration
I'm conducting a synthesis involving crown ether and Pd catalyst.
In many papers, prior to column chromatography, they filter crude mixture through a Celite pad.
I tried to, but leakage of Celite ...
2
votes
0answers
22 views
Is there a way to experimentally determine if a copolymer has a random monomer distribution or a blocky monomer distribution?
I prepared a styrene-butadiene copolymer with a polar modifier. The expectation is that the copolymer is "random". Is there a way to confirm this using standard characterization techniques?
0
votes
1answer
46 views
Using samples in titrations
I've never done an experiment before. So, the methodology provided in this pdf is quite confusing.
Link to the pdf: https://www.canterbury.ac.nz/media/documents/science-outreach/vitaminc_iodine.pdf
So,...
1
vote
1answer
74 views
How can I filtrate Pd2(dba)3 and P(o-tol)3? (Celite filtration failed)
I am conducting an organic synthesis involving Stille coupling, using $\ce{Pd2(dba)3}$ and $\ce{P(o-tol)3}$ as catalysts. Reaction solvent is toluene in which the catalysts also dissolve. Many texts ...
2
votes
0answers
54 views
what does Area(A) in Randles-sevcik equation refer to? geometrical area of electrode or electrochemical active surface area/
In the Randles-Sevcik equation,
$$i_p = 0.4463 \ nFAC \left(\frac{nFvD}{RT}\right)^{\frac{1}{2}}$$
we have an area $A$ in the formula. is this the electrochemically active area or geometrical area? ...
1
vote
1answer
60 views
Why d and s orbitals overlap even when there is considerable difference in their energies?
In my grade 11 chemistry NCERT textbook, its written that hybridization happens when orbitals of almost same energy overlaps.
But S orbital and D orbital have significant difference in their energies. ...
4
votes
1answer
72 views
Does pH gets affected by pressure? [closed]
My attempt- I thought that pH is h+ ion concentration and change in volume will change its equilibrium according to le chatelier's principle .
But I want to know is it correct or it needs some ...
-2
votes
1answer
69 views
How to make plasma in microwave (without grapes please)?
So, I have my School Science Fair next month. We are working in teams of five with one 7th, 8th, 9th 10th, 11th and 12th grader. We were planning to make plasma in microwave but the grape method just ...
7
votes
4answers
550 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: ...
-5
votes
2answers
112 views
What would happen if the alpha particles directly hit the electrons in the gold foil in Rutherford's experiment? [closed]
What would happen if the alpha particles directly hit the electrons in the gold foil in Rutherford's experiment?
Would it get ionized or is there no probability of such a thing happening ?
2
votes
1answer
74 views
Is it possible to filter Stille catalysts using syringe filter?
I'm conducting an organic synthesis involving Stille coupling.
Stille coupling uses $\ce{Pd2(dba)3}$ and $\ce{P(o-tol)3}$ as catalysts.
Both catalysts dissolves in toluene which is the solvent of my ...
2
votes
1answer
55 views
Can the paper in thin layer chromatography be any type of paper?
I'm doing a chemistry chromatography lab that wants me to recreate anything I want. I decided to measure how far a pigment goes in each color for the same brand, but I'm stuck at the paper part. I ...
1
vote
0answers
31 views
Thickness of proton exchange membrane (Nafion)?
I am looking into using a proton exchange membrane for a bio-energy cell experiment. Previous scholars have been using Nafion as a PEM to place between the anode and cathode (air-cathode). the ...
-2
votes
1answer
68 views
How to heat up a barrel drum? [closed]
I am experimentalist, and I am unsure on how to proceed about a question I have for an experiment. In the experiment, I would like to heat up a drum barrel like:
It is made of HDPE, and I would like ...
0
votes
0answers
19 views
Can ethanol and heat during distillation cause degradation/dissolution of vinyl tubing leading hot vapors of the distillate to the condenser?
I'm a chemist and a qa lab, and we occasionally test herbal remedy products from one of our customers for alcohol content using a distillation, then using the specific gravity of the distillate to ...
0
votes
1answer
419 views
At which temperature does a concentrated aqueous solution of sodium chloride begin to boil? [closed]
We know, solutes dissolved in water increases the boiling point of water. This question is an MCQ. The options are 96,99,100,104 degree Celsius. The correct answer is 96. Why? If the boiling point ...
