Questions related to the methodologies, equipment requirements and safety considerations of any experimental procedure.

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Removing the hydrazine byproduct from the mitsunobu reaction

Looking to remove the hydrazine byproduct left after the mitsunobu reaction. Using DIAD and polymer bound triphenyl phosphine. The reduced diad is coeluting with my product on silica. My thoughts for ...
3
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1answer
60 views

Is there a means to measure pH without indicators?

I have created a solution that should contain hydroxide ions. Therefore, the pH > 7, but is there any way to roughly estimate the pH in absence of any indicator? Maybe using current, or checking ...
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0answers
14 views

What kind of suspension liquid should be used with bulk ferrofluid (so it does not stain the glass)

I am an Engineering student and I'm currently on a project meant to demonstrate some properties of magnetic fields. I want to put my bulk ferrofluid in a glass bottle with a suspension solution (A ...
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2answers
14 views

Chemical reactions in SFE?

What are the chemical reactions and/or chemical processes that take place during SFE(supercritical fluid extraction)? Namely supercritical $\ce{CO2}$.
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2answers
47 views

Why pipetting with a 30° angle?

After seeing https://www.youtube.com/watch?v=qorl6rKLmRs, I was left to wonder why use a 30° angle between the flask and the pipette when emptying it. I can imagine it is important to touch the flask ...
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1answer
45 views

Recrystallization of two unknown compounds?

I managed to separate a binary mixture(in solid form) of two unknown substances into two individual solid compounds. For the separation, I used an acid-base extraction with dichloromethane, NaOH, and ...
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0answers
7 views

Synthesizing monodisperse PbS quantum dots

For a research project, I am trying to synthesize lead (II) sulfide quantum dots using the method of Li et al. (http://pubs.rsc.org/en/Content/ArticleLanding/2010/CE/b917833c#!divAbstract). Basically, ...
3
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2answers
37 views

Refluxing with tilted condenser

Can you reflux without any problems/dangers with a tilted condenser (e.g. because you don't have enough space in your fumehood)? I would say there isn't a problem, because both the surface area of the ...
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1answer
59 views

Separation of Binary mixture?

I will be given a binary mixture containing two unknown compounds(the mixture could be either liquid or solid- I don't know yet). The plan of the experiment is to identify the two compounds. So my ...
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1answer
29 views

How do you perforate a teflon sheet?

I have a sheet of thin unperforated teflon that I need to perforate by tomorrow for a lab I work in. None of my coworkers know how to perforate the sheet. Does anyone know how I can do this using ...
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0answers
8 views

Silica, Alumina and Sodium Hydroxide from Caustic Soda solution

I had a solution containing Silica and Alumina in caustic soda. I need to extract the same from the solution separating Silica, Alumina and sodium hydroxide. How can I do it? Please provide the ...
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1answer
99 views

Synthesizing Aspirin Question

Take as example this http://njcmr.njit.edu/distils/lab/aspirins/nap4.html or even better this http://wwwchem.csustan.edu/consumer/aspirincons/aspirincons.htm Wash the crystals with 2-3 ml of ...
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1answer
49 views

identification of zinc/aluminium/magnesium with copper sulphate solution

We are doing an experiment and would like to be able to identify zinc/aluminium/ magnesium . Would a copper sulphate solution work ? I hear that it turns black on contact with zinc, stays clear on ...
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0answers
26 views

Why are multiple extractions better than a single extraction? [duplicate]

I'm extracting $\ce{N-(4-butoxyphenol)-N'-(4-dimethylaminophenyl)thiourea}$ from thiombutosine (anti-leprosy drug) tablets. I'm doing this extraction with hot ethanol. My question is why are 4 ...
3
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2answers
78 views

Why is a volumetric flask shaped the way it is?

A volumetric flask does not look like an Erlenmeyer flask, but has more of a pear shape. Is it just to distinguish more easily between them while they are on the shelf?
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2answers
57 views

Preparation of phenylamine/aniline

This is the procedure I carried out in class: Reduction of nitrobenzene by using tin and $HCl$ acid After the completion of the reaction, $NaOH$ added to neutralize excess acid and dissolve any ...
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2answers
43 views

Different type of distillations

I know that fractional distillation is used to separate two liquids that are miscible in one another and have close boiling points. However, I am really confused about vacuum distillation and steam ...
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0answers
19 views

To model early fluid flow which types of pumps should be used?

I have I microchannel test rig , I want to push a 150-300 ml/hr from water in my test , I would like to know which pump type i can use ?
5
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1answer
63 views

Steam distillation- how it actually works?

To obtain phenylamine after it is formed from the reduction of nitrobenzene with tin, we carried out steam distillation. This is what I learned in class: "During the process,steam is injected ...
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1answer
20 views

How do you measure the chemical composition of stuff? [closed]

I'm not a scientist of any sort, I'm just curious. Here are some specific examples. Let's say I collect some rainwater and I want to find out what is in it that isn't water. How would you do that? ...
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2answers
46 views

Using Spectrophotometer to analyse enzyme reaction

Suppose we have two enzymes with concentration of 1X and 0.1X We then add a substrate and incubate the mixture for 1 or 10 or 20 minutes.( So,there will be total of six samples.) Question ...
4
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2answers
77 views

What is an effective experiment to demonstrate the safety of wearing leather shoes while experimenting in the chemistry lab?

Quite often (from my own experience anyway), one of the safety rules in a school (high school or university) laboratory is that the students must wear leather shoes. I like to demonstrate some of ...
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261 views

How to calculate lattice parameter only using planes and d spacing

I am trying to find lattice parameter of a hexagonal crystal, usually i uses cellcalc for calculating lattice parameter of a crystal struture. In that software it asks only two queries one is details ...
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0answers
22 views

How to get defect-energy level diagram from PL data

I am reading this article Phys. Chem. Chem. Phys. , 2011, 13, 14902-14905 and seen that the authors have drawn a image of defect level using PL data Can you explain me how this diagram can be drawn ...
2
votes
1answer
101 views

Belousov-Zhabotinsky reaction

The Belousov-Zhabotinsky reaction is a very fascinating one. The Chemistry behind the reaction concerns thermodynamics and equilibrium. I want to perform the experiment, but I'm not able to find ...
2
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1answer
46 views

Uncertainty propagation question?

Question related to uncertainty propagation. I was taught that when adding/subtracting measurements, add the absolute uncertainties, and when multiplying/dividing measurements, add the relative ...
3
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0answers
270 views

Calculation of Atomic weight percentage in AAS

I am currently doing doping studies in a system similar to this ($A_{x}B_{1-x}$) and i have to find atomic weight percentage of $B$ element using atomic absorption spectroscopy(AAS). I have prepared ...
2
votes
1answer
411 views

How can I determine the boiling point of a compound using simple distillation?

I've graphed a distillation curve (temperature against volume of distillate) from the data obtained from a simple distillation experiment. The substance can be any of methanol, ethanol, 1-propanol or ...
3
votes
2answers
151 views

How to quickly cool a test tube without cracking it?

Is there a way to safely cool a heated test tube quickly without cracking it due to sudden thermal stress in the glass? One thing that I tried was blowing on it, cooling it in slightly lukewarm water ...
2
votes
1answer
88 views

How to properly work with potassium HMDS

What is the proper procedure for working with KHMDS? I would like to use it to deprotonate a compound and have a bottle of KHMDS in toluene. Does it need to be handled under inert atmosphere? And ...
3
votes
1answer
34 views

Less maintenance-dependent continuous pH testing

I am creating an automated chemical component mixing system (DIY project). One of the features required is continuous monitoring of pH value in my main solution. I do not need it to be very precise, ...
6
votes
1answer
198 views

Is it safe to condense water into a liquid nitrogen trap?

I'm trying to remove water from an imidazolium salt (i.e. dry the salt). However I want to know if it is safe to remove the water under vacuum. Is it safe to condense water into a liquid nitrogen ...
5
votes
2answers
554 views

What is the procedure of designing a salt bridge for a galvanic cell?

I'm doing an experiment where I'm measuring the effect of changing the $\ce{Cu^{2+}}$ ion concentration on the voltage in a copper-zinc galvanic cell. I'll be doing at least five trials for each of ...
3
votes
1answer
471 views

How is the time for a test tube in a centrifuge determined?

I came across some hairy math that's used for analytical centrifugation, mostly for things like determining the sedimentation rate for liquids. However, what I don't understand is how someone ...
3
votes
1answer
104 views

What is a “lagged bath”?

First question, and this is one I've searched for in vain. In the context of setting up cooling baths, I've come across the term "lagged" bath. I cannot extract what this means from any available ...
2
votes
1answer
565 views

Why should I add lithium bromide to my GPC eluent?

I'm running gel permeation chromatography (GPC) of a polar, uncharged polymer (acrylamide-based) in a polar solvent (dimethylformamide). The literature recommends adding a salt to the eluent; for my ...
1
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1answer
44 views

How are crystals formed from a gas?

In crystallization, crystals are formed from liquids by cooling. How can crystals be formed from a gas by cooling?
3
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1answer
1k views

Inherent error in mass and volume?

In one of my chem classes I had to do a lab that involved finding the mass and volume of a substance. I did three trials and for my mass I got 9.3g, 9.3g, and 9.4 g. For my volume, I got 9.7ml, ...
3
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1answer
923 views

Pipetting strong acid with plastic material

Can I pipette concentrated sulfuric acid using a plastic pipette tip? Will either the plastic or the acid be affected?
2
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1answer
136 views

How would I neutralize a PEP (Phosphoenolpyruvic) acid?

PEP (Phosphoenolpyruvic acid) is acidic but I need to make it neutral. I need a solution (pH 6-8) of PEP in a final 1 mL volume with a concentration of 100 mM. How would I make this?
5
votes
1answer
569 views

How did Michael Faraday melt Sodium Chloride?

Michael Faraday melted sodium chloride in a silver spoon and ran an electric current through the molten salt, which released chlorine as a gas and left pure sodium behind. Sodium chloride melts at ...
3
votes
1answer
193 views

What is the correct name for this lab technique [crystallization]

Take a glass rod and rub vigorously the wall of the flask, the substance will crystallize out of the solution. Take a fire polished stirring rod and etch (scratch) the glass of your beaker. The small ...
4
votes
1answer
65 views

How do you determine the amount of acrylamide in foods such as baked fries?

There are many food studies which determine the concentration of a substance in a food item. For example, this study determines the concentration of acrylamide in solid foods like fries. By what ...
7
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1answer
184 views

How to translate the mobile phase from thin layer chromatography to column?

I recently was told that once you find a good solvent mixture for separation on thin layer chromatography (TLC), you should only use 10% of the more polar solvent (for silica) when you run your ...
3
votes
2answers
713 views

How long does it take to run a MS/MS experiment

I am not planning to do these types of experiments but I would like to know the order of magnitude of the time it takes to run an LC-MS/MS experiment. Let's assume that I have the sample prep ...
6
votes
3answers
369 views

Experimental calculation of solubility product constant

I mixed $6.0~\rm mL$ of $.01\:\rm M$ $\ce{Pb(NO3)2}$ and $6.0~\rm mL$ of $0.02\:\rm M$ $\ce{KI}$ and $8.0~\rm mL$ of water and a precipitate (barely) formed. I calculated the $K_{sp}$ with ...
12
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2answers
304 views

What can I do if I don't get a phase separation between my organic and water phases?

Solvent extraction in a separation funnel is a very common method in preparative organic chemistry. But sometimes you don't get a nice phase separation between the organic and the water phase. What ...