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.
1,451
questions
3
votes
0answers
23 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-...
-1
votes
0answers
25 views
Help calculating log P
What is the correct way to calculate log P of a drug?
Two 3ml samples of 1%w/v solution of ibuprofen in octanol were prepared, a pH 2 buffer is added also.
0.5ml of the octanol layer is taken and ...
2
votes
0answers
25 views
Will changing the salt in the salt bridge change the voltage produced in a galvanic cell?
I have used zinc sulfate and copper sulfate as the solutions, and used zinc and copper electrodes.
For salt bridge I took lithium, potassium, calcium, sodium and zinc nitrates. The results are as ...
-1
votes
0answers
31 views
Betaine HCl solution at neutral pH
I was trying to make a $2\text{M}$ solution at $\text{pH}\, 7.5$ of Betaine $\ce {HCl}$.
I started by weighing out the appropriate amount of Betaine $\ce {HCl}$, added some water and started stirring. ...
-1
votes
1answer
35 views
How can I find out how much caffeine is in my decaf tea and coffee?
I know that the decaffeination process is not perfect and that it leaves some caffeine. I've looked online and there was a company in 2009 that offered caffeine test strips but they seem to be no ...
1
vote
0answers
30 views
Calcium chloride as a drying agent for solutions
I'm aware of the reaction Calcium chloride has with water vapour and how it can therefore be used as a good and inexpensive drying agent but could that be applicable for solutions?
For example if ...
0
votes
1answer
25 views
Hazard and precautionary statements
Is there a scientific database where one can find all the H and P statements for all chemicals? I would like to avoid using wikipedia but I can't find a database from a trusted source.
-2
votes
1answer
31 views
Helium container [closed]
Imagine a vacuum flask-like container. If we filled the main compartment with helium and the vacuum compartment with high-pressure gas would helium still escape?
Let's ignore the leakage from the ...
2
votes
1answer
60 views
Reagent notation: meaning of dash(-) and line(|) or slash(\) in reagents
I've seen a lot of reagents which have a slash between two compounds, such as Lindlar's catalyst which is $\ce{H2}$ along with $\ce{Pd|BaSO4}$. I know that the sulphur is a poison here but in general, ...
-1
votes
1answer
29 views
What happens if you do not allow time for an exothermic reaction to cool down?
I realise I did not give some time for the chemicals (which are releasing heat during an exothermic reaction) to cool down first and instead, I added another chemical substance to the reaction mixture ...
0
votes
0answers
16 views
What Math and chem fields should I study for working with materials science [closed]
I'm coming into my first year at a 4-year university after finishing my associates at a two year school. I think that I am interested in focusing on materials science, I feel like there is still so ...
1
vote
3answers
152 views
+50
Removing denatured Crystalbond?
I have some water-soluble crystalbond that is attached to silicon and, because of some overheating (to about 150 Celcius) during a final processing step, the crystalbond seems to have charred (white/...
0
votes
0answers
51 views
Is there a reusable and safe exothermic reaction
I am looking for an alternative to the sodium acetate reaction used in e.g. heat packs. I need something similiar but that generates more heat, so that I could for instance warm 200ml of water to a ...
-2
votes
2answers
72 views
pH probe reading greater than 14
Today I was using my pH meter on wastewater samples but the meter was reading values near 14 and sometimes greater, I changed the probe with the spare one and it read well (sure I calibrated before ...
5
votes
3answers
289 views
Does partially/completely removing solid shift the equilibrium?
For the reaction: $$\ce{P4(s) + 5O2(g) <=> P4O10(s)}$$
Let's say the reaction is at equilibrium, and SOME $\ce{P4O10(s)}$ is removed from the reaction. Will that affect equilibrium? My ...
0
votes
0answers
38 views
Why does dissolved oxygen concentration decrease with increasing atomic number of metals?
I am looking at how metal ions ($\ce{Fe^2+}$, $\ce{Ni^2+}$, $\ce{Cu^2+}$, $\ce{Zn^2+}$, and $\ce{Ag+}$) affect the biochemical oxygen demand in water and used the Winkler's method to find out the ...
0
votes
0answers
20 views
steam distillation vs fractional distillation
I am a high school student and I am a little confused in the techniques used to purify organic compounds, for e.g we study in steam distillation we reduce the external pressure on the compound to be ...
2
votes
1answer
30 views
Copolymer purity, what does AN / MA / MS mean?
I would like to buy some polyacrylonitrile (PAN) powder from GoodFellow and I have the choice between these two products:
AN316010, quality : Copolymer (99.5% AN / 0.5% MA)
AN316020, quality : ...
-5
votes
1answer
34 views
Aluminum electrodes for NaCl [duplicate]
Upon using aluminium Electrodes for a concentrated solution of NaCl, i conducted electrolysis on the solution for nearly 4-5 hours. There was definitely a gas possibly hydrogen being evolved at the ...
1
vote
1answer
63 views
NaCl electrolysis with copper electrodes
Considering the aqueous $\ce{NaCl}$ is already concentrated. If we were to use copper electrodes instead of inert graphite electrodes:
Would copper react with the evolved chlorine gas to give $\ce{...
0
votes
3answers
68 views
How do I prepare citric acid solution (from anhydrous powder) of accurate concentration, given that the solution volume expands when water is added?
I attempted to prepare saturated citric acid solution from anhydrous powder. According to online data, the solubility limit was 59.2 w/w at 20 °C, i.e. 59.2 g citric acid in 100 mL water. To ensure ...
-1
votes
1answer
48 views
Electrolysis of Nacl with aluminium Electrodes
I conducted an experiment to find out the difference in products/ the final solution whilst using different electrodes. On using copper I obtained a teal blue soluble salt I believe to be $\ce{CuCl2}$ ...
1
vote
1answer
45 views
What are the benefits of using zero capillary voltage for discarding fractions in LC–ESI–MS/MS?
In the second episode of The Association for
Mass Spectrometry & Advances in the Clinical Lab (MSACL) podcast, namely Getting going with mass spectrometry : Josh learns chromatography (aired 2021-...
1
vote
1answer
32 views
Purging submersible with nitrogen
I do a lot of short term ocean field deployments where system electronics are self contained in a submersible enclosure. A new project I'm working on requires a long term deployment in the deep ocean. ...
1
vote
0answers
27 views
Free on-line dissociation constants
Is there a decent on-line source for dissociation constants for acids and bases as CRC alternative?
This chemistry stackexchange old answer no longer has valid links:
Is there an online database of ...
0
votes
0answers
31 views
Titanium Dioxide and plastic
How would you recommend attaching a film of anatase to a flat polycarbonate surface without compromising its photocatalytic characteristics? The self cleaning paints that I have seen are generally ...
-2
votes
0answers
17 views
Comparing the acidity levels of different types of tea
I am a high school student and have the opportunity to create a project on a topic that I want. I am thinking of making one on how the acidity of tea is affected by the type and addition of milk and ...
3
votes
0answers
44 views
Which acetate salt is blue and turns yellow when dissolved in water?
***Update
Some questions I am considering to try to answer this question;
When dissolving the powder in acetic acid, which ions are present?
From what I've read, I haven't found any acetate salts ...
0
votes
0answers
34 views
Stirring bar cleaning
I have a small question concerning the stirring bars cleaning. I use mine in BOD test wastewater for 5 days and I want to clean them so my question is can I soak them overnight with sodium ...
1
vote
2answers
83 views
Disposal of Silver Halides dissolved in Ammonium Hydroxide
I was reading the Lab Manual for Chemistry prepared by the NCERT . While going through the the test for Chloride ions (pg 88) I came across the following Hazard Warning :
The solution obtained after
...
-1
votes
1answer
56 views
How to prepare a 10% alcoholic KOH solution? [closed]
I am confused actually. A 10% alcoholic KOH solution means that there is 10g of KOH in 100 ml of ethanol, or 10g KOH in 100 g of ethanol or something entirely different?
Also, I understand that the ...
1
vote
1answer
65 views
What is “silanol activity”?
In a previous post about how pyridine failed to move much from the baseline of a TLC, I was told to look into "silanol activity". However, I was unable to find a textbook-style description. ...
0
votes
0answers
45 views
How to measure purity of nitrogen gas in a “homemade” way?
Is there any indicator or a way of measuring purity of nitrogen? The lab-way of doing things is out of my reach and I was thinking about a DIY way. I want to decrease oxidising atmosphere in a ...
0
votes
0answers
18 views
Purpose of water bath- rate of formation of precipitate in haloalkane hydrolysis
In a high school experiment for observing the rate of formation of precipitate with Silver Nitrate in the hydrolysis reaction of different haloalkanes (Chloroalkane, Bromoalkane, Iodoalkane), a water ...
0
votes
1answer
65 views
How to make foggy and cloudy plastic fully transparent?
I used sandpaper of different grits to sand the surface of plastic. The surface is smooth but it looks dull after sanding. I read that one could use toothpaste to remove the foggy look but it did not ...
0
votes
1answer
56 views
The quantum mechanics behind periodicity of elements
Especially in high school/first-year undergraduate chemistry courses, we learn with great dedication the periodicities along groups and periods. There are various useful and interesting trends.
I ...
0
votes
0answers
33 views
Doubt in a nomenclature for equilibrium constant
Why is there $H,N$ and $CO$ attached to the suffix of equilibrium constants? Particularly how to use these as suffixes? Nothing can be extracted from the reaction. There are many $H,N$ and so on like $...
10
votes
1answer
462 views
Photochemical reduction of benzophenone: why inverted flask?
I've come across an interesting protocol for photochemical reduction of benzophenone to benzhydrol (diphenyl methanol) with sodium alcoholate in alcohol, the 2nd protocol in https://prepchem.com/...
0
votes
0answers
41 views
How reliable is spectrometry in the determination of the oldest material Startdust?
After reading one of the latest findings by scientists, Stardust was considered the oldest material on earth. However having not much of an experience with chemistry, I was intrigued upon how ...
-1
votes
2answers
82 views
In the Gold Foil experiment, did Ernest Rutherford's alpha particles hit the same spot every time or did he direct the emitter to different spots?
When reading and learning about the gold foil experiment, the alpha particles mostly go straight through the gold foil and some get deflected or bounce back but it doesn't say anything about the ...
1
vote
0answers
25 views
Standard practice for keeping salts dry
I should point out first that I'm not a chemist, but I'm currently doing a little bit of chemistry; this should clarify that I don't have formal training in a chemistry lab (other than some basic chem ...
1
vote
1answer
43 views
BPS & BPA treatment with 80% Ethanol
Background: BPA and BPS (Bisphenol A/S) are artificial estrogens and therefore toxic chemicals for us. They are used in the coating of thermal paper. Thermal paper is used to print in-store receipts. ...
1
vote
0answers
23 views
Flux a specific concentration of a tracer constituent of a gas
I need to flux 250 ppm of CO2 at 1000 ml/min.
I have a gas system with a tank containing CO2 (CO2 at 5000 ppmvol, Oxygen 21%vol and Nitrogen the rest), connected with a mass flow controller (MFC1, ...
1
vote
0answers
22 views
What is the best way to clean Lovibond tintometer quartz cuvette used for oil?
I work in a laboratory where we regularly check edible oil color by using a Lovibond colorimeter. Some people suggested me to wash the quartz cuvette using soap solution.
But I am thinking about ...
4
votes
0answers
65 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 ...
-1
votes
2answers
166 views
What is the essence of chemistry? [closed]
I am an engineering student who loves physics but didn't quite enjoy chemistry.
a. When I was in high school chemistry to me was something not as inspiring as physics but in which I couldn't solve ...
0
votes
0answers
21 views
Is it possible for graphite which has shed off metal rods during water electrolysis to bond with the hydrogen being produced to form hydrocarbons?
I recently conducted a simple experiment for school involving the electrolysis of water.
I changed the concentrations of an ionic compound to determine its effect on the rate at which the products of ...
-1
votes
1answer
72 views
Is it possible to heat up water using chemicals? (Meaning no outside source of heat like electricity, or gas) [closed]
I am asking in terms of heating something small like a 10oz cup of water with it also being safe to consume. It would have only need to heat the water for around 1-2 hour(s).
0
votes
1answer
50 views
Why are some weak acid equilibrium approximations invalid in very dilute solutions?
Using two approximations for the dissociation of a weak acid, we can write
$$K_\mathrm{a}= \frac{[\ce{H+(aq)}]^2}{[\ce{HA(aq)}]}$$
One of these two approximations we use is that the concentration of ...
1
vote
3answers
72 views
Need reactants for a rocket [closed]
I am doing a project in chemistry at the moment to build a rocket out of materials that can be easily bought and that react strongly to create thrust.
I was wondering if anyone knew a good chemical ...
