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 ...

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54 views

Purification of Ethanol

In Vogel's organic book, they have mentioned that in the Lund and Bjerrum method of purification of ethanol, magnesium is added, which forms ethanolate. But they said to activate the magnesium first ...
3
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0answers
26 views

Choosing the instrumental techniques for chemical analysis [on hold]

Since every technique has its goods and its bads characteristics, it's a bit hard for me to choose between them to determine specific elements, methods such as UV-VIS spectroscopy, IR spectroscopy, ...
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0answers
14 views

How photoluminescence (PL) spectroscopy works

Photoluminescence (PL) spectroscopy is used to find the energy levels in a compound but how does PL spectroscopy works? After exciting a material with a particular wavelength whether PL machine looks ...
2
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2answers
322 views

How common are automated pipetting systems

It's clear that automated pipetting is faster than doing it manually, but how common is it for a lab to have an automated pipetting system, and what usually are the circumstances that a lab have ...
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2answers
24 views

Identifying MgCl2 or CaCl2 in solution

I have an aqueous solution of either $\ce{MgCl2}$ or $\ce{CaCl2}$ in solution with $\ce{K2SO4}$. There is a white precipitate that forms on the bottom that does not dissolve when $\ce{HCl}$ is added ...
11
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1answer
69 views

Interlocked Cyclic Compounds

Being new to chemistry, there may ought to be some properties I couldn't understand fully. One of them being cyclic compounds. One particular question about this is, whether these cyclic compounds, ...
2
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1answer
19 views

Crucible heating apparatus

I have seen some heating apparatus for a crucible use a retort stand with a large metal ring attached to the boss head to support the clay triangle as shown below. Instinctively, I would have ...
5
votes
1answer
60 views

Determining (approximately) the amount of a strong base needed to change a buffer's pH by a certain number of units

I'm measuring buffer capacity by titrating $\ce{NaOH}$ into a buffer of $\ce {H3PO4 + NaH2PO4}$. I'm measuring buffer capacity by recording the amount of $\ce{NaOH}$ required to increase the ...
5
votes
1answer
62 views

Method of deriving some properties or possible method of synthesis of a specific monomer

This is kind of like two questions but since they're related I have put them together. Consider a monomer under a hopefully anatomically correct name 'Phenyl Carbolithia Divinylene Oxide ...
3
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1answer
38 views

Using Distribution Coefficient to Determine Mass and Percent of Acid Extracted

The $K_\mathrm{D}$ (distribution coefficient) of coffee water at $25\,°\mathrm{C}$ is $7.8$ in a methylene chloride/water system. If there is $2.0\,\mathrm{g}$ of caffeine in $200\,\mathrm{mL}$ of ...
5
votes
1answer
53 views

Investigating a factor affecting buffer capacity

I'm preparing for an experiment to investigate some factor affecting buffer capacity. At the moment, I'm looking at using a $\ce{NH_3}$ ($2\,\mathrm{M}$) $+$ $\ce{NH_4Cl}$ buffer, but I'm not sure ...
1
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1answer
27 views

Does DMT-Acetate become Polar in H2O, with added NaCl?

I'm extracting DMT (N,N-dimethyltryptamine) from Acacia confusa via acid/base. I extracted the DMT with $\ce{H2O}$ and acetic acid, converting it to DMT-acetate. Here, I used a non polar solvent, ...
3
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2answers
60 views

How to calculate the percentage of calcium carbonate in sea shells in an experiment

We have a investigation in my chemistry class in which we must calculate the amount of calcium carbonate in sea shells. We can have as many sea shells as we wish, lab equipment, and hydrochloric acid ...
1
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1answer
62 views

Finding Cation of Unknown Salt in Solution from Precipitate

I should probably add that I was originally given an unknown solid mixture of 2 salts. I separated the insoluble salt out by centrifuging and then decanting. I found that the insoluble salt is ...
8
votes
1answer
64 views

What happens when I use cyclohexanol to prepare cyclohexene?

I've done a student experiment using cyclohexanol to prepare cyclohexene. We mix $10.5~\mathrm{g}$ cyclohexanol and $5~\mathrm{mL}$ $85\%$ $\ce{H3PO4}$ in a $50~\mathrm{mL}$ flask, then distill while ...
6
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1answer
27 views

Determination of mercury in AAS

Its known that the only method to determine mercury in atomic absorbtion spectroscopy is the cold vapor method. What is the reason that mercury can't be determined with other methods, such as flame, ...
3
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0answers
32 views

How can I purify ethanol from formic / boric / salicylic acid?

I need some ethanol pure and strong enough for technical purposes (fuel, solvent, cleaning agent, dissolving rosin for soldering flux, etc.). Food quality is not required though, denaturated one is ...
3
votes
1answer
31 views

Can I get an accurate temperature reading from a flask with a built-in thermometer well?

I recently purchased a flask with a built in thermometer well, but I have discovered that simply setting a rod thermometer in the well does not produce a very accurate reading. I was wondering if ...
3
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0answers
49 views

Target temperature for infused cooking oil

A little context: I make craft chili oils for friends and family. I use a two-step infusion process. First, I infuse the oil for flavor by simmering spices in the oil held around 250 degrees ...
5
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0answers
21 views

Atomizers in AAS

Electeothermal atomizer ( graphite furnance ) and flame atomizer, are the instruments which help us to convert the analyte into the gas state and they both achieve that. My question is, what's the ...
0
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1answer
22 views

How to attach a liebig condenser to a flask for reflux heating?

I know it's probably a stupid question, but I can not figure this out. I have a liebig condenser that I usually use for distillation with a Kjeldahl bulb, which makes it easy to attach to a flask ...
11
votes
1answer
144 views

Failed synthesis of aspirin - too much H2SO4

Last week, I tried synthesizing acetylsalicylic acid - the reaction is shown below - using $\ce{H2SO4}$ as a catalyst. However, as the title suggests the synthesis failed as I used too much ...
4
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0answers
27 views

Gold recovery under vacuum

Can gold recovery with acid peroxide (ap) method be done under vacuum or left in sealed chamber, as opposed to placement in open air?
6
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2answers
150 views

How is drift due to static electricity eliminated from an analytical balance?

I've recently encountered a problem when using an analytical (0.1 mg accuracy) scale to determine the mass of a sample of ferrocene powder. The reading in the balance seems to drift either upwards or ...
2
votes
1answer
46 views

Auxochrome groups

Functional groups like $\ce{OH}$, $\ce{NH2}$, attached to nonsaturated compounds (chromophores) are called auxochromes. These groups tend to shift the wavelength to the infra-red area which is called ...
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0answers
20 views

Ink / formulation chemistry: What lab requirements

Little open information can be found on the requirements of the manufacture, development and testing of gel and printing inks. It seems that most ink manufacturers have their own specific lab ...
3
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1answer
28 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 ...
3
votes
1answer
147 views

Thermodynamics and Coffee

Heyo, I'm sure you all know of the experiment where you take a mixture of ice and water, plop some salt in there and the temperature of the solution progressively drops. The salt increases the entropy ...
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2answers
29 views

Why are hollow cathode lamps used for atomic absorption spectroscopy?

In 1955, it was proposed that hollow cathode lamps are good emission sources for monochromatic radiation, and thus for atomic absorption spectroscopy (AAS). In looking into the topic, I've read that ...
3
votes
1answer
38 views

Instrumental methods of analysis

I am taking the instrumental methods of analysis course. Our job is to find the unknown mass of $\ce{Fe}$ which is added, by measuring the absorbance of different solutions with ortho-fenantroline. ...
4
votes
1answer
35 views

What mechanisms might make a substance travel different distances on the same TLC plate?

When doing TLCs to monitor reactions, it is considered good common practice to not only spot the reactants and the reaction mixture (likely after some mini-workup), but also to include a ‘cross-spot’: ...
3
votes
1answer
60 views

Effect of impurities on enthalpy of fusion of ice

When I freeze water with some impurities (1% NaCl by mass), the mixture seems to have a much lower enthalpy of fusion that pure water. The impurities cause the freezing point to depress to 0.6°C. I ...
4
votes
2answers
129 views

How can I turn natural gas from liquid to gas?

I hope I am not too off topic. I couldn't find a more suitable stack-exchange site for this, so if there is a better one, please point me to it. My question is the following: I am working on a ...
1
vote
2answers
31 views

How do I create azeotrope mixture?

I want to decrease the boiling point of a compound. So I need to create an azeotrope mixture from two or three compounds. Where can I find out how make it?
3
votes
1answer
28 views

Practical question about rotovap solvent collection

This is a practical question about the use of rotary evaporators ("rotovap"). So I'm asking for answers from people who actually use the things. A rotovap typically uses a cold condenser to condense ...
6
votes
1answer
71 views

How can I measure the internal temperature of a solid metal?

I’m heating up several metal blocks as part of an experiment to determine their specific heat capacities. In a nutshell, I’m heating the blocks of known mass to 100 °C, then adding them to an ...
7
votes
0answers
29 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 ...
2
votes
1answer
24 views

Decomposition of hexaurea-chromic-chloride-trihydrate

I am sitting over a TG diagram of the decomposition steps of hexaurea-chromic-chloride-trihydrate ($\ce{[Cr(CO(NH2)2)6]Cl3 \cdot 3 H2O}$) and cannot really make sense of the products it might ...
0
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0answers
28 views

Stirring the reaction between hydrochloric acid and a powdered substance

For an experiment, I'm adding several substances (as powders) to hydrochloric acid, and measuring the temperature changes to calculate enthalpy. However when adding the powders, the mixture requires ...
3
votes
1answer
32 views

How to lose as little heat as possible to the surroundings from an endothermic reaction?

For an experiment, I'm adding several substances (as powders) to hydrogen chloride, and measuring the temperature changes to calculate enthalpy. What is a container I could perform it in (other than a ...
4
votes
2answers
167 views

Why use a salt bridge at all in an electrochemical cell?

I was reading about electrochemical cells and I really don't understand why a salt bridge is needed. Can't you just combine the solutions? I've found a lot of webpages explaining electrochemical cells ...
-1
votes
1answer
104 views

Experimental difficulty with the iodine clock reaction

I did the iodine clock reaction using sodium metabisulfite and potassium iodate. As I understand it, increasing concentration is supposed to speed up your reaction rate. I did 10 trials. The first 5 I ...
0
votes
1answer
36 views

Spin coat of Graphene oxide on glass slides

I would like to spin coat Graphene oxide on the glass slides and intend to have a thickness of 100nm/0.1micrometre. May I know what is the amount of Graphene oxide to be poured onto the glass slides, ...
3
votes
0answers
36 views

How to store distilled water

How can I store distilled water without introducing impurities? I'm going to be doing so electrical studies of pure water and ice and I need a way of keeping the water pure during the experiments. ...
4
votes
2answers
48 views

Diluting down solutions method

I'm designing an experiment and it involves testing various concentrations of solutions, and I will be testing 5 in total. I proposed to make up a stock solution, and distribute it evenly in 5 ...
6
votes
2answers
139 views

In which country is it allowed to practice non-clandestine amateur chemistry?

I travel a bit so am flexible where I live, and have taken a recent interest in chemistry to try to gain an understanding of physical reality. I find learning from textbooks to be good, but want to ...
4
votes
1answer
80 views

Is there an experiment that visibly shows the effects of metastability?

I am attempting to create an experiment to show the effects of metastability to a public audience and get people excited about science. More specifically, I am wondering if there is any sort of liquid ...
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0answers
62 views

Calculating the Molarity of an Ion?

I'm completely stuck on this one - I was doing an experiment in a lab and now I cannot find the molarity of an ion in a solution. I've looked everywhere on the web but after 2 hours of searching I ...
0
votes
1answer
23 views

Sulfur Doped Titanium Dioxide

I'd like to know why my $\ce{TiO2}$ sol gel did not get coated nicely on my 200 gsm fiberglass? Here my solution, 5 g of tween 80, 40.15 ml isopropanol, 3.4 ml titanium isopropoxide, 0.62 ml sulphuric ...
4
votes
1answer
63 views

How to remove a stuck stopper from a flask

I had a question about how about how to remove a stopper that has been stuck in the neck of a 100 mL round bottom flask since I forgot to wipe the neck of the flask. A salt was formed in the 100 mL ...