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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22 views

How can I use sunlight to heat a RBF and reflux a reaction?

This may seem like a off topic question but I really need help on it. I am currently working on a polymerization reaction in which I'm breaking down plastic polymers into smaller molecules. However, ...
2
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0answers
6 views

Limits on contaminant size in filtration for extraction, and standard alternatives?

Following up on How to perform solvent extraction of a solid I realized that I haven't quantified the size of the contaminants. I know they aren't soluble in acetone and the target is, but I don't ...
9
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2answers
351 views

Are PTFE stir bars resistant to all lab solvents?

It seems like glass-coated stir bars are a specialty item. Standard stir bars are coated in PTFE. Is PTFE resistant to all typical lab solvents? Or is there a reference to check to ensure it is ...
2
votes
1answer
42 views

How do I find the empirical formula for Co(C2O4)*H2O with mass of Oxalate and Oxide Product?

I have the formula $\ce{Co(C2O4)*H2O}$ in a reaction that forms cobalt oxide $\ce{Co3O4}$ – My data here says that my oxalate hydrate weighed 0.3283 g and my product oxide weighed 0.1158 g which I ...
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0answers
31 views

Blood alcohol differential equation. How it is found?

Can somebody explain how is the following differential equation found? It is about the blood alcohol content. See this article, pages 3 and 4: ...
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0answers
20 views

How do I set my vacuum regulator for filtration?

I know about what pressure the gauge reads on my hand pump when I am doing filtration at max vacuum (greatest vacuum that does not break the filter) which is about 20 inches $\ce{Hg}$ vacuum. How do I ...
1
vote
1answer
30 views

What is CIF (a PCB developer) and what does it do?

I made a PCB (printed circuit board) for the first time, and the process included covering the board with the shape we want, exposing the board to UV light and then putting it in a developer which ...
3
votes
1answer
34 views

Alcohol in the bloodstream modeled by differential equations

Does anyone know any good references which use partial differential equations to model the alcohol concentration in the bloodstream? I'm a mathematician, so I'm searching for a rigorous mathematical ...
0
votes
1answer
43 views

Cleaning silver - which method is better? [duplicate]

What is the advantage of this approach over polishing the silver with an abrasive? "Silver tarnish is an outer coating of silver sulfide, $\ce{Ag2S}$, formed when silver reacts with trace quantities ...
3
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0answers
25 views

Calculating K Value of a Clock Reaction

Uncertainty Not Included Some Units Not Included R2 value calculated from Header (Concentration, 1 over Concentration and LN Concentration) vs Time Column of ...
1
vote
1answer
38 views

Help determining the amount of hexavalent chromium to use?

My friend is working on her Masters and needed my help confirming some math. The literature she is referencing says to expose her fish to $3~\mathrm{mg~L^{-1}}$ of hexavalent chromium. We at our ...
2
votes
1answer
33 views

How to perform solvent extraction of a solid

Suppose I have a solid compound from which I want to extract a target chemical I know is soluble in acetone. So I crush and mix the compound in acetone, dissolving the target and suspending the ...
3
votes
1answer
31 views

Distillation Heating Mantle Setup

In my lab courses, we were taught to use textbooks off the shelf as elevating props to adjust the heights of heating mantles to the right height during distillations, but I was wondering if there was ...
3
votes
2answers
63 views

How do I setup the electrodes for cyclic voltammetry on a capacitor made on dry copper sheets?

I'm trying to measure capacitance of a cell I'm creating. It's composed of two copper-sheets with nano-material coated on one side, sandwiched with a membrane and wetted with $\ce{KOH}$. All of the ...
6
votes
1answer
41 views

Does phosphoric acid remove stainless steel electropolished layer?

Electropolished stainless steel has a high corrosion resistance due to the oxide film that is created during electropolishing. The film mainly consist of chromium(III) oxide. Phosphoric acid is ...
5
votes
0answers
29 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 ...
6
votes
0answers
43 views

How Do I Identify What Impurities Are in My Product?

I am writing a lab report for Organic Chemistry about a multi-step synthesis that we conducted. While our product has the proper melting point, its IR spectrum has peaks not present in the respective ...
6
votes
1answer
73 views

Proper use of vacuum pump during vacuum distillation

I am preparing to do a vacuum distillation and am unsure exactly how to manage the vacuum. The vacuum pump I have is a two-stage rotary vane pump which is capable of 250 microns or lower. It has a ...
6
votes
1answer
62 views

H2SO4 with ethanoic acid reaction?

Earlier today I was preparing an ester (propyl ethanoate) and I noticed that instead of putting the propanol, ethanoic acid and $\ce{H2SO4}$ in the test tube and warming it (taking time and external ...
5
votes
0answers
29 views

Reduction of vanadyl ion

I want to reduce vanadyl to vanadium (III), can somebody please suggest some appropriate methods for it? I am trying to make a redox flow battery for a project but I have only vanadyl sulfate.
1
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0answers
20 views

Looking for a Chemistry Demo Resource Group

I'm looking for some kind of email list, forum, or group that discusses chemistry demonstrations. I'm working on an improvement to a demo that's been used for a few decades at my institution and I'm ...
6
votes
1answer
65 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?
10
votes
1answer
146 views

Why do some solvents bubble more than others when boiling?

This question about boiling milk reminded me of my everyday lab work at the rotavap: Some solvents and solutes are feared for the intense bubbling they create while the solution is boiling — be it at ...
5
votes
1answer
124 views

How to get a precise reading from pipette?

While doing titrations, we are instructed to use pipette and they demonstrated how to use a pipette. But still after all this, we face difficulties of how to take precise reading from pipette. ...
5
votes
1answer
54 views

how to destroy excess iodomethane in reaction mixture?

I have used iodomethane to make a phenolic $\ce{OH}$ group to $\ce{OMe}$ group in Aq+Methanol medium. I have added water to precipitate the product of mine and will evaporate the solvents but I cant ...
16
votes
1answer
634 views

How can an inexperienced chemist determine the chemical structure of a molecule?

I'm a fairly inexperienced, but nonetheless interested chemist, currently planning a small project for the coming summer: I want to isolate an unknown chemical from a plant and determine it's chemical ...
0
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0answers
22 views

Qualitative Analysis of Anions

From the image above, if you all could take a loot at step 1a. It makes no sense to me. I do not understand why adding $\ce{CH3COOH}$ has any effect on the solution whatsoever. What is the point of ...
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votes
1answer
20 views

Cathode rays produce heat when they fall on a matter

I have studied this many times in my Chemistry F.Sc-1 book that cathode rays produce heat when they fall on a matter but this thing is beyond my comprehension that how they produce heat?
4
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0answers
22 views

Linear PEI Solution Making

I'm making a solution with linear poly(ethyleneimine) $\ce{[CH2CH2NH]_{n}}$. The bottle indicates that the substance is hygroscopic and must be dealt with under inert gas. Is this really necessary? ...
9
votes
1answer
79 views

Dissolving metal reductions

Could reduction of an organic compound by reacting it with sodium dissolved in $\ce{NH3}$ still proceed if a metal such as aluminium were used instead of sodium? I'm not sure about the aluminium amine ...
5
votes
1answer
116 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 ...
2
votes
1answer
62 views

Separate precious metals from catalytic converter

I am looking to separate the small quantities of platinum and palladium in a catalytic converter. However since these are very inert metals I am unsure how to proceed about doing so. Melting the ...
3
votes
0answers
35 views

Choosing the instrumental techniques for chemical analysis [closed]

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, ...
1
vote
0answers
27 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
votes
2answers
336 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 ...
0
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2answers
40 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 ...
13
votes
1answer
85 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
votes
1answer
32 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
67 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
65 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
votes
1answer
51 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
86 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
vote
1answer
43 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
votes
2answers
129 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
vote
1answer
86 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
77 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
votes
1answer
51 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
votes
0answers
37 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
40 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
votes
0answers
51 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 ...