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.
1,505
questions
3
votes
0answers
42 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 ...
-1
votes
0answers
29 views
0
votes
0answers
37 views
Chemistry Equations [closed]
How do I know what the equation of a reaction is without knowing what the products are? Am i meant to do trial and error and just guess?
Eg:
When 3.4g Pentane was burnt in excess oxygen, 165kJ of heat ...
3
votes
0answers
46 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
60 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
0answers
16 views
Question about Oxygen Managment [duplicate]
I am working on ideas for a more hard Si-Fi, and I am wondering through what processes one could theoretically take the carbon dioxide we breath out and break it down into Carbon and Oxygen. I am ...
0
votes
1answer
39 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
47 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 hardly goes up. (see image below)
...
2
votes
0answers
24 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
38 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
Why does iodine to give off so much vapour? [duplicate]
It is reported that when placing iodine in a breaker and letting it sit, over time the iodine will slowly give off a large amount of vapour. The question is why does it give off so much vapour. I was ...
2
votes
0answers
18 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
43 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
votes
0answers
31 views
What's the right way to prep anhydrous potassium ferrocyanide from potassium ferrocyanide trihydrate?
Orgo student here.
I've got some potassium ferrocyanide trihydrate I tried dehydrating with no success.
I put 20 g of potassium ferrocyanide trihydrate into a 30 mL crucible driven up to 150 C for 2 ...
1
vote
1answer
59 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
42 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? ...
5
votes
0answers
42 views
Why is surface tension of water decreasing as sodium chloride concentration increases? [duplicate]
For my IB chemistry IA, I am measuring the impact of salinity concentration on the surface tension of water (i am using distilled water). My hypothesis is:
As the concentration of salt increases, ...
1
vote
1answer
50 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
67 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
66 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
244 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
87 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
59 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
51 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
27 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
65 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
16 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
196 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 ...
0
votes
0answers
29 views
Why is Retention factor for Iodide greater than Bromide?
I did a separation of Bromide and Iodide ions using paper chromatography technique for 0.3% solutions of Bromide and Iodide of sodium. I got the Retention factor equal to ~0.71 for Iodide and ~0.47 ...
3
votes
0answers
34 views
Why neglecting Bradford Solution Volume in the assay?
I would like to know why do we not need to take account of Bradford agent solution in dilution calculation?
For example, $\pu{2.5 \mu g mL-1}$ BSA will calculate from $\pu{0.4 \mu L}$ of $\pu{1 mg mL-...
3
votes
0answers
41 views
Can color-changing leuco dyes be used to indicate when a certain molecule binds to another in a textile fabric?
Thermochromic leuco dyes change color when the temperature changes. I want to use leuco dyes to make a color-changing fabric. However, instead of using temperature to induce color changes, I want the ...
1
vote
1answer
32 views
Three Phases in TFM test instead of two
I am currently trying to perform the Total Fatty Matter (TFM) test on soap and for some reason I am getting three phases instead of two.
The surfactant used is SLES and other reagents include hot ...
1
vote
0answers
21 views
Reason for three phases in total fatty matter test on soap [duplicate]
I am currently trying to perform the Total Fatty Matter (TFM) test on soap and for some reason I am getting three phases instead of two.
The surfactant used is SLES and other reagents include hot ...
2
votes
2answers
107 views
How to find the angle of emission of an X-ray during impact of accelerated cathode rays?
X rays are produced when accelerated cathode rays strike a metal target or a metal anode.
How can we find the angle at which the X-ray is emitted from the metal anode or the target when the cathode ...
-4
votes
1answer
64 views
Practices while using a boiling tube
When using a boiling tube to boil a liquid, I am frequently advised to move the boiling tube in and out of the Bunsen flame and when the liquid starts to boil, remove the tube from the flame for a few ...
0
votes
1answer
46 views
Synthesis of 1-naphthaleneacetic acid: Methods
I am trying to synthesizing 1-naphthaleneacetic acid from naphthalene and monochloroacetic acid. I found some patents and papers, and I have tried to synthesis but the yield is low. I used iron powder ...
0
votes
0answers
57 views
How can I weigh the compound that melts at room temperature?
I am conducting an organic synthesis experiment involving 2,3,5-tribromothiophene.
The melting point of 2,3,5-tribromothiophene is about 25-28 ℃, so it melts easily during weighing.
Whenever I weigh ...
1
vote
0answers
43 views
Procedure for laboratory synthesis of tertiary amines [closed]
I am having difficulty finding a procedure for making tertiary amines in the lab, any is fine but I am specifically interested in tributylamine.
3
votes
0answers
23 views
Extract seaweed iodine from petroleum ether and cyclohexane
I'm working on iodine extraction from seaweed by using petroleum ether and cyclohexane. I have already observe the presence of iodine in the solution but I don't know how to extract the iodine in a ...
0
votes
1answer
65 views
Detection of sulphide in solution also containing sulphate
Question:
The reagent(s) that can selectively precipitate $\ce{S^2-}$ from a mixture of $\ce{S^2-}$ and $\ce{SO4^2-}$ in aqueous solution is(are):
(A) $\ce{CuCl2}$
(B) $\ce{BaCl2}$
(C) $\ce{Pb(...
4
votes
1answer
130 views
Can we use silver nitrate to distinguish between chloride and carbonate salts?
Initially, we are given a solution containing two salts, they can be either carbonate or chloride salts (we do not know their composition initially).
Generally, $\ce{AgNO3}$ is used as a confirmatory ...
3
votes
0answers
18 views
Safety concerns (Cyanide): Dicyandiamide + Polyamine condensation reaction
I am attempting to synthesize a poly-amine polymer by condensation between dicyandiamide (also known as cyanoguanidine and dicyandiamine) and diethyltriamine. The polymer is a kind of dye fixative ...
5
votes
1answer
35 views
Carbon 11 radiolabeled inhaled Beta-2 agonist or corticosteroids, is it possible?
Background
Positron emission tomography (PET) is a highly sensitive imaging modality that can provide in vivo quantitative information of biological processes at a biochemical level. PET relies upon ...
0
votes
0answers
31 views
Measuring Cylinders — small or big?
My teacher often recommends the usage of a smaller/more narrow measuring cylinder over a larger one while performing experiments but why is that? Does it help in accuracy in any way?
0
votes
0answers
42 views
What is the literature value of the activation energy of the reaction between iodate and bisulfite?
I explored the Arrhenius equation using the reaction between potassium iodate (containing the IO3- iodate ion) and sodium metabisulfite (bisulfite ion), however I can't find a literature value to draw ...
-1
votes
2answers
61 views
Enthalpy vs. delta enthalpy
I haven’t really found a clear answer.
Enthalpy is measured as the sum of internal energy (kinetic and potential energy) and pressure times volume. However, I don’t really see the value of measuring ...
0
votes
1answer
52 views
How to make silicic acid, potassium silicate or calcium silicate?
I am a student of tropical agriculture. I am taking the class of agronomic chemistry and plant nutrition. I want to make use of silicate source I have at home for e.g. zeolite, wood ashes, ...
2
votes
1answer
27 views
Diffusion of multiple gases at once
Graham’s law of diffusion states the rate of diffusion between two gases is inversely proportional to their molar masses. Now, this is helpful when we are focused on two gases. But that is rarely the ...
1
vote
3answers
135 views
Safe chemical reactions to start a campfire [closed]
I'm looking for a way to start a small fire electronically with widely available chemicals. It would be great if they are safe to use with metals (not necessarily). But the biggest requirement is that ...
2
votes
0answers
25 views
Is there a known value for the molar extinction (absorption) coefficient for amylose and amylopectin iodine complexes?
I am doing a colorimetry experiment with starch, and have a theoretical model based on Beer's law. To solve it, I need a known value for the molar extinction coefficients of amylose and amylopectin ...
